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    Firbolg in the Playground
    Join Date
    Oct 2012
    Boston, MA

    Default Mecha System Development--First Ideas for Parts

    Hey everybody A while back, I started developing a system for a mecha game, and had a small thread going for it. I got about as far as the combat system and a very rough skill list, then kinda put it on hold for a while--but now I'm getting this project back on track, and I'd love to hear thoughts on the new stuff I've come up with. Please keep in mind that this is a work-in-progress, and as such is far from complete and somewhat disorganized.

    Right now, I'm focusing on developing rules for different parts--after all, who wants to play a mech system without full customization? So far, I've figured out the different stats for each part of the machines' basic bodies, and got a set of stats for weapons. I am, of course, planning to have way more types of parts than the ones presented here, so if people are paying attention to this, I'll update it with new part types I come up with.

    First, a repost of what I have so far for the combat system, so that the weapon stats make more sense.


    Johnny the Union pilot is standing guard outside a base when he spots an approaching Coalition scout. Since he has orders to engage any hostiles who come within his line of fire, he initiates combat with the enemy!
    First, Johnny and the gamemaster both roll to determine whose turn comes first. I haven’t decided how this works yet, so I’ll skip it for now.
    Johnny wins, so he gets the drop on the enemy. It is now his turn. At the start of his turn, Johnny has two actions to spend—these are the resource he uses to do things during a battle. Most actions that Johnny could take would consume one action, but some would me more involved and time-consuming and require two, while others are particularly quick and easy and can be done for free.
    Johnny decides that the first thing he wants to do is move to a position with better cover. He spots a barricade nearby that will help protect him from the enemy’s attacks, so he spends one action to move his mech behind the barricade. Now that he is in a good position, he decides to open fire on the enemy. He thus spends his remaining action to fire a shot with his mech’s assault rifle.
    Aiming at the enemy, Johnny rolls his dice and adds his rifle’s Accuracy bonus. The rifle is a reasonably accurate weapon, and he gets a total result of 65%. Attempting to avoid the incoming fire, the Coalition pilot (controlled by the GM) rolls his dice and adds his mech’s Evasion bonus. The scout mech is light and nimble, but the pilot rolls poorly, getting only a total result of 43%—lower than Johnny’s attack. The shot connects with the Coalition mech.
    Johnny now has to determine how badly his shot damaged the enemy. He rolls his dice again, this time adding his rifle’s Damage bonus. His total roll is 38%, since the rifle is not particularly powerful. However, his enemy’s mech has armor that may block some or all of the damage. The Coalition pilot rolls his own dice and adds his mech’s Armor bonus, getting a result of only 25% due to his scout mech’s light armor. Subtracting his Armor roll from Johnny’s Damage roll, his mech takes a total of 13% damage.
    Johnny has now used up all his actions, so it is the Coalition pilot’s turn. His mech has taken some damage, and he doesn’t want to risk any more—if his mech is damaged to 100%, it will be destroyed. But there’s no nearby cover that will offer him a clear line of sight to Johnny’s mech. In order to reach the nearest suitable cover, he needs to run, so he spends both his actions to move. His mech dashes as fast as possible to the cover of a nearby boulder. He now has some protection from Johnny’s fire, but since he’s used both his actions to move a greater distance, he doesn’t have time left to fire any of his weapons. It’s now Johnny’s turn again.
    The two combatants will continue taking turns until the fight ends—either when one mech is destroyed or retreats, or until something else happens to end the battle.

    This example only shows a few of the most basic combat mechanics—there are far more things pilots can do with their mechs during a firefight. Some mechs are equipped with energy shielding that blocks damage, others with cloaking technology that makes them invisible, and still others with even more powerful and diverse technologies and capabilities. However, most actions in combat can be accomplished by variations of the simple mechanics presented above.
    Below is a more comprehensive list of key terms and actions in combat.

    The Basics

    Combat in Animus proceeds in turns, with each participant taking their turn to act, and the rotation beginning again after it finishes.
    The success or failure of actions taken in combat is determined by rolling percentile dice, adding or subtracting from the total based on your character and the situation, and comparing the result to a target number or another similar die roll.
    While it is not necessary, it can be helpful to represent combat with miniatures on an inch-square grid. This can help keep track of positioning and how many combatants there are. The rules assume that maps and miniatures for combat are on a scale of one inch on the table to five feet in the game.


    The first step in any battle is to roll for initiative—this is what determines the order in which participants take their turns. Mechanics for initiative are still under development.


    Every mech has a movement speed, based on various factors. This determines how far the mech can move. In order to move during combat, a pilot spends an action to move a distance within the limit of their movement speed.
    A pilot can spend both their actions to double-time, moving double their speed in one turn. This grants them an extra 10% to their Evasion bonus against enemies making reaction attacks from Overwatch (see below).


    Some mechs can equip systems that allow them to fly. In this case, they will have a flight speed separate from their overland movement speed. Other than this, and the fact that flying mechs can move vertically, flight works exactly the same way as overland movement.


    In order to destroy enemy mechs, a pilot must make effective use of their various weapons. While there is variation in the detailed mechanics of different types of weapons, they all follow the same basic process for attacks.
    Attacking normally takes up one action, with some rare exceptions. Most weapons can attack twice in the same turn, if both actions are spent. In order to attack, the attacker first selects their target, which must be within their weapon’s maximum effective range. If they have a weapon with Precision, they decide now what part of the enemy they want to target—otherwise, the attack is automatically assumed to be aimed at the target’s body. They then roll percentile dice, and add to the total the accuracy bonus of the weapon with which they are attacking, plus any other relevant bonuses or penalties. This total determines the required value of the target’s evasion roll. The target then rolls percentile dice and adds their mech’s evasion bonus, plus any other relevant bonuses or penalties. If the total of this roll is higher than the attacker’s attack roll, the attack misses—if it is lower, the attack connects.
    If an attack hits successfully, the damage of the attack must then be determined. To do this, the attacker rolls percentile dice and adds their weapon’s damage bonus, plus any other relevant bonuses or penalties. Then the target rolls their percentile dice and adds their mech’s armor value. The total of the armor roll is subtracted from the total of the damage roll, and the remainder is deducted from the integrity of the part that was hit.


    Sometimes, it’s better to wait an enemy out than try to attack them right away. In situations like this, the best thing to do is go on Overwatch. Overwatch is like delaying an attack until later—it allows you to wait for an opening and fire as soon as you see your target. Entering Overwatch only consumes one action, but it can only be done at the end of your turn. You will remain on Overwatch until the beginning of your next turn. While on Overwatch, a combatant waits until an enemy moves within their line of sight, and then attacks them immediately (if they are within range). Afterwards, they leave Overwatch and cannot make more attacks in this manner. Attacks made from Overwatch are called reaction attacks, and suffer a -10% penalty to accuracy.

    Melee Attacks

    Melee attacks work exactly like all other attacks, except that their effective range will always be listed as “melee”. This means that the attacker must be adjacent to the target in order to attack.
    Also, melee weapons cannot be blocked by shields (see below).

    Missiles and Explosives

    Missiles consist of an explosive warhead attached to the front of a rocket-propelled module designed to be fired from a mech-mounted launcher. They work similarly to other weapons, but with a few differences.
    Missiles tend to do much more damage than other weapons. In addition, when they explode, they can damage all parts of a target rather than just the body (see below), and can even damage multiple targets over a large area. However, they travel more slowly than bullets, which can allow the target to intercept them if they are quick enough.
    When a combatant makes an attack using a missile weapon, the target can make an intercept roll to try and shoot down the missile before it hits (provided they have a weapon powered up and operational). An intercept roll is just like an attack roll—in order to shoot down a missile, the intercept roll must be higher than the attack role of the attacker. If a missile is intercepted, it has no effect. If the target fails their intercept roll, they may still roll to evade the missile as normal.
    When a target is hit by a missile, damage and armor rolls are made as normal. However, damage from a missile applies to all parts of the target’s mech rather than just the body—all parts take the same damage rolled. In addition, more powerful missiles can damage large areas around the target. Missiles with this capability will list their blast damage separately from their direct-hit damage, as well as their area of effect. AOE missiles require two evasion rolls—one to avoid a direct hit, and another to escape the blast radius. If the second roll is successful, the target chooses any space adjacent to the blast radius and places their mech there. If a missile’s blast radius is greater than the target’s movement speed, they cannot escape the blast—they automatically take blast damage.

    Damage and Hull Integrity

    When a mech is hit in combat, its hull will take damage. If the damage becomes severe enough, the mech’s systems can be crippled—it may even be destroyed entirely.
    Every mech has five sections that can be damaged—head, body, right arm, left arm and legs. Most weapons are not accurate enough to target specific sections of an enemy mech in combat—by default, attacks are assumed to target the body. Each part has its own integrity total, and is usually damaged separately. The maximum hull integrity of each part is 100%--when it reaches 0%, it is disabled.
    Each part has different effects when it is disabled. If the body of a mech is disabled, the entire mech is destroyed, since the body contains both the cockpit and most of the vital systems. Destroying another part of a mech does not affect the entire machine, but a mech cannot activate any systems attached to a disabled part—for example, if your mech’s right arm is fitted with a laser cannon, and another pilot disables that arm, you cannot fire the cannon until the arm is repaired. However, when a part is disabled, any power that was being allocated to systems attached to that part is freed up to be used by other systems.
    If a mech’s body is disabled, the pilot rolls percentile dice. On a roll of over 50%, the mech explodes, causing damage to the surrounding area. Detailed rules for exploding mechs are under development.

    Firing Into Melee

    Shooting ranged weapons into melee combat makes it much more difficult to hit one’s intended target. When firing at two or more mechs that are engaged in melee, the attacker assigns an equal range of results on a set of percentile dice to each, and then rolls their dice. The result of the roll determines which target is hit. This is done after designating the part of the target that is being aimed at, if applicable.
    For example, Jill is aiming her mech’s sniper rifle at an enemy mech that is currently engaged in melee with one of her allies. She wants to cripple her target’s sensors, so she decides to aim for the enemy mech’s head. Because there are two combatants in melee, Jill assigns a range of 1% to 50% to her intended target, and a range of 51% to 100% to her ally. She then rolls her percentile dice, getting a roll of 71%--she hits her ally’s mech in the head, destroying its cameras and blinding it. Oops.

    Cover and Concealment

    Mechs are built to take a pounding, but your armor can only withstand so many shots. In order to maximize your protection from enemy attacks, the best thing to do is to stay in cover.
    The way cover works is simple. Any time there is an object of at least a certain size and thickness between you and your enemy, it counts as cover. There are two levels of cover—partial and full. While in partial cover from an enemy, you gain a 20% increase to your evasion bonus against their attacks—in full cover, the bonus is 40%.
    It’s important to remember that cover doesn’t automatically protect you from every angle of attack. If an enemy has unobstructed line of sight to you, the cover bonus doesn’t apply against their attacks.
    Another good way to avoid getting hit is to not be seen. This can be accomplished with terrain that provides concealment. Like cover, concealment is divided into partial and full levels. If you have partial concealment from an enemy, they take a -20% penalty to attack rolls against you—with full concealment, the penalty is -40%. Cover is similar to concealment, but represents different situations. If your enemy’s shots are blocked by a wall you are hiding behind, that’s cover—if you are hidden by dense foliage (that will do nothing to actually stop incoming bullets), that’s concealment.


    Many mechs can equip systems that project a Kinetic Interdiction (KI) Field, more commonly called a shield. Shields function a lot like armor, but with some differences. Below is an example of a turn in combat during which a shield comes into play.

    Johnny’s mech has taken some serious damage from the Coalition scout’s laser sniper rifle, and he needs to take steps to protect himself. Powering off his jump jets—he wasn’t using them anyway—he spends his first action to turn on his mech’s shield battery. Once activated, it projects a KI Field with a shield rating of 25%. He spends his remaining action to fire another shot from his rifle, missing by a fair bit.
    The Coalition pilot’s turn begins. He needs to get to better cover, so he spends his first action to move to a safer position. Having moved already this turn, he can’t fire his laser sniper rifle, so he switches over to his light machine gun and takes aim at Johnny. He’ll need to breach Johnny’s shield before he can damage his mech.
    He rolls his attack, getting a result high enough to overcome Johnny’s evasion attempt. His shot connects with Johnny’s shields. The Coalition pilot rolls his damage, getting a total of 45%. However, instead of an armor roll, Johnny makes a shield roll to prevent damage. This works the same as his armor roll, but he uses his shield bonus instead of his armor bonus. His total roll is 30%, so the Coalition scout’s LMG deals 15% damage to Johnny’s shields. His mech is protected and takes no damage, but the shield is weakened—if it is damaged 100%, it will fail, exposing his mech to further attacks.

    Shields essentially form an extra layer of armor that prevents the user’s mech from taking damage until it has been breached. However, shields are notably different from armor in that if they go a certain number of turns, determined by the shield battery’s recharge threshold, they will regain some of their power and regenerate partially. For example, if Johnny manages to hide and prevent further damage to his shields for two turns, they will recharge by 5%, bringing their integrity back up to 90%. For this reason, shields can often be much more effective in combat than standard armor, and are often relied upon strongly by heavy combat mechs.

    And now, here's what I have so far for parts.

    Mech Parts and Stats

    Every mech is composed of multiple modular parts. The ability to swap out parts depending on the situation is one of a mech pilot’s greatest strengths, and learning the best combinations of parts for a desired function is essential if you want to be successful. In order to do this, you must understand each different type of part and what it does.
    Parts fall into two main categories—components and attachments. Components are essential parts of a mech that it must have in order to function, such as a body and legs. Because every type of component is essential, all mechs are assumed to be designed with the necessary power supply to run all their components—because of this, components do not draw from the mech’s maximum power supply. However, there are far fewer types of components than there are of attachments, and less freedom of choice in which ones to equip. Attachments are non-essential (but still very useful) parts like weapons, wings and shields. Pilots can choose from a wide array of attachments depending on their mission, but the number of attachments they can power and use at the same time is dependent on their mech’s maximum power output. Learning the most efficient combinations of parts will lead to great success.
    The types of parts, and the stats of each one, are described below.


    The central chassis of every mech is made up of five components—a body, a head, two arms, and a pair of legs. A given model of mech will include all five of these components, usually designed to work together as effectively as possible for a particular function. Many pilots, however, choose to mix and match components from multiple models of mech to create a new combination with elements designed for multiple functions. Such a method is entirely valid, but be warned that the diversity it offers comes at the expense of focus.
    Each component helps determine a mech’s stats. The stats possessed by a mech, independent of its attachments, are listed and described below, sorted by the component from which they are derived.


    • Maximum Power (PWR)—the maximum total of power generated by the mech’s engine. This determines how many attachments the mech can have active at once. Different attachments have different power requirements, and the total power required by all active attachments cannot exceed the mech’s PWR limit. Note that the number of attachments a mech can have fitted is separate from how many it can have powered—a mech may be able to fit more attachments than it can power at once, forcing the pilot to keep some of them turned off.
    • Armor Rating (ARM)—the armor bonus of the mech. This helps it resist damage from attacks.
    • Body Attachment Slots—the number of attachments the mech can have fitted directly to its body. Attachments fitted to the body usually include things like shield generators, wings, and other utilities.
    • Attachment Bonuses—the types of attachments for which the power requirement is reduced when using this body. Note that this reduction applies for attachments equipped to any location on the mech, not just the body itself. Attachment bonuses from all parts stack with each other.


    • Head Attachment Slots—the number of attachments the mech can have fitted to its head. Attachments fitted to the head are usually various types of sensors.
    • Attachment Bonuses—as above.


    (Remember, every mech can equip two arms. These are treated as individual parts, and can be of different models.)

    • Arm Attachment Slots—the number of attachments the mech can have fitted to this arm. Attachments fitted to the arms are usually weapons, though they also include certain defensive and utility tools.
    • Attachment Bonuses—as above.


    • Movement Speed (SPD)—how fast the mech can move overland when using these legs.
    • Evasion Rating (EVN)—the evasion bonus of the mech when using these legs. This helps it avoid being hit by enemy attacks.
    • Jump Distance (JMP)—how high and far the mech can jump when using these legs.
    • Leg Attachment Slots—the number of attachments that can be fitted to the legs. Attachments fitted to the legs are usually designed to enhance movement, including jump-jets, dash-jets, and motor enhancements.
    • Attachment Bonuses—as above.


    Attachments are the greatest determining factor in a mech’s capabilities. They include everything from weapons to shields to cloaking to repair tools. Unlike with components, mechs are not inherently designed to support all possible attachments—whether you can fit an attachment to your mech depends on its available slots, required skill levels, and maximum power. However, even for specialized mechs, there will be a wide array of attachments to choose from, allowing you to tailor your capabilities to your preferences and the mission at hand.
    There are many types of attachments, each with a different function, and within each type, there are different makes with different capabilities. However, each type of attachment will use the same basic stats for all of its makes. Several types of attachments are described below.


    The classification of weapons is extremely broad, and includes everything from assault rifles to plasma swords. However, all weapons use the same basic stats, which are as follows.

    • Weapon Type—indicates the general class of the weapon. This can be projectile, energy, melee, or explosive. The type of the weapon determines the skill required to equip it.
    o Weapon Class—the more specific type of weapon, including rifles, swords, etc.
    • Required Power (PWR)—how much power is required to turn on and use the weapon.
    • Fitting Location—indicates which parts of the mech the weapon can be equipped to (usually the arms).
    • Effective Range (RNG)—the maximum distance at which you can attack with the weapon.
    • Accuracy Rating (ACR)—the weapon’s accuracy bonus. This determines how hard it is to hit with the weapon.
    • Damage Rating (DMG)—the weapon’s damage bonus. This determines how easily the weapon destroys enemies.
    • Required Skills—which skills are required to equip the weapon, and what level they must be.
    • Attributes—many weapons have special characteristics that drastically alter their capabilities. These will be indicated under this stat with a special keyword. The definitions of each keyword are listed below.
    o Explosive—all explosive-type weapons possess this attribute. When a weapon with Explosive damages an enemy mech, the total damage is applied to all parts of the target simultaneously (each part takes the same damage as the total rolled).
    o Melee—all melee weapons possess this attribute. A weapon with Melee automatically ignores enemy shields.
    o Blast—an attribute possessed by certain powerful explosive weapons. Weapons with this attribute can damage multiple targets over a large area. These weapons will have their blast radius and blast damage indicated along with the attribute itself. For full rules on blast damage, see the Missiles and Explosives section of the Combat chapter.
    o Precision—a weapon with precision can target specific parts of an enemy mech when making attacks. However, in order to do this, the attacker must not have moved their mech in the same turn. Additionally, even if the attacker does not target a specific part, they take a penalty of -20% on their accuracy roll if they have already moved in the same turn. For full rules on damaging mech body parts, see the Attacking section of the Combat chapter.
    o High-Precision—this attribute is the same as precision, except that if the user of the weapon has already moved on their turn, they cannot attack with the weapon.
    o Armor-Piercing—this attribute allows a weapon’s attacks to slice through enemy armor. This attribute will always be accompanied by a specific value. When an enemy hit by this weapon makes an armor roll, if the attacker’s damage was equal to or higher than the Armor-Piercing value of the weapon, all damage up to that total is automatic and cannot be affected by the target’s armor roll. For example, an attack is made with a weapon with Armor-Piercing 20%, with the total damage roll being 41%. The target rolls 28% for armor, but instead of reducing the damage to 13%, it is instead reduced only to 20%, the Armor-Piercing value of the weapon. If the attacker’s damage roll is lower than their Armor-Piercing value, the damage cannot be reduced by armor—all of it is dealt automatically.
    o Shield-Piercing—this attribute is identical to Armor-Piercing, but affects the target’s shields (if any) rather than their armor.
    o Slow—weapons with Slow can only be fired once per turn, regardless of how many actions the attacker has available.
    o EMP—the weapon applies an EMP effect when it hits an enemy. For details on EMPs, see the E-war and Cyberwar section of the Combat chapter.
    o Fortification—if the user of a Fortification weapon is in cover and has not moved in the same turn, they gain a 20% bonus to accuracy rolls with that weapon. Additionally, while the user is in cover, Fortification weapons can make reaction attacks without incurring the normal -10% penalty.
    o Silent—firing a Silent weapon does not alert nearby targets to your position, making such weapons excellent for covert missions. However, once any enemies notice they are under fire, they may be able to determine the attacker’s position by other means than sound.

    So, any comments on what I've got so far? Suggestions on more to add? I'm all ears.
    Last edited by Amaril; 2013-05-15 at 09:37 PM.

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