Gun/Diebuster d20?!

[ZebulonCrispi]

My current and first homebrew project: To create a set of d20 rules for combat in the Gunbuster (http://en.wikipedia.org/wiki/Gunbuster)/Diebuster (http://en.wikipedia.org/wiki/Diebuster) universe.

My initial reaction to this idea when it sprang into my head was that it was completely impossible, and I was criminally insane for having even thought of it. The second thought was that no, it could probably be done, but it would take some HEAVY fiddling, and it was probably a bad idea to take something so complex as a first project. My third thought was that life is too short to spend not doing insane things, so here I am.

Scale
The biggest hurdle to overcome in creating a d20 Diebuster (I'll be focusing on Diebuster alot more than Gunbuster, as it is more awesome) system is the scale. 100+ foot robots fighting tens of thousands of space monsters. Enemies the size of entire planets. Can d20 handle something like this? I think it can, but it requires a bit if re-interpreting of the system.

I will be using a two-layer system: One layer for on-foot PC interactions, and one layer for Buster Machine combat. In each layer, things like HP and Strength scores will have completely different meanings.
The Normal layer will function in a way very similar to d20 Modern or Future, haven't thought about that too hard yet. Besides, most PCs wouldn't be fighting much other than other humans outside of their Buster Machines.
The Space layer barely notices humans and the like - HP, physical stats, and size categories are completely reworked to reflect the epic scale of Diebuster battles. A large conventional spacecraft might have about 30 HP, with planets sporting a couple thousand.
When the two layers try to overlap, a pair of simple rules can be used for interactions between them:
1: Any Normal scale being attacking any Space scale being inflicts no damage.
2: Any Space scale being attacking any Normal scale being kills in instantly.

This is my current tenative re-working of the size categories for the Space layer:
{table=head]Category|Range|Examples

Diminuitive|<1m|Cat, Dog

Tiny|1m-4m|Humans

Small|4m-16m|Combat suits, Express space monsters

Normal|16m-64m|Buster Machines, Smallest STMC

Large|64m-256m|Conventional Spacecraft, Space Monsters

Huge|256m-4km|Massive Spacecraft, Cruiser-class STMC

Gargantuan|4km-256km|Battleship Exelio, Massive STMC

Colossal|>256km|Planets[/table]

Buster Machines
Building a Buster Machine is an important part of any Diebuster character, as all characters are assumed to be Toplesses (Buster Machine Pilots). However, I won't be using Mecha rules for this. The Buster Machine is less of a conventional robot and more of a quasi-magical force of personality in the shape of a robot. To accomodate this, Buster Machines will have their own character sheet, and level up along with the pilot.

A Buster Machine has its own hit die, Armor, abilities, movement, and physical stats. Its mental stats, skills, saves, and BAB are taken from the pilot. When rolling stats, roll one set of 9 stats, and distribute them among the 6 stats of the pilot and the 3 stats of the Buster Machine.

I haven't gotten far into the actual construction method for Buster Machines, but they'll most likely be going on something similar to Behold the Void's Bleach d20 classes - a Melee Buster class, a Projectile Buster class, and an Energy Buster class. Each will have its own AC progression, hit die, and abilities. I'll work more on that after studying the series a bit.

Bad guys
There are three main groups of enemies in the Diebuster universe:

Humans
People can never get along very well, and it's very likely that the players will have to fight other people. On foot, this'll be like any d20 Modern/Future battle. In space, combats between Buster Machines are highly rare, but can happen, and should generally be reserved for major plot-based confrontations.

Space Monsters
The most prevalent of mankind's enemies are the Space Monsters. Uncountable in number, they form a blockade around the entire solar system, traveling in swarms numbering in the tens of thousands and occasionally attacking planets or space stations. It is almost impossible for anything but a Buster Machine to fight off the Space Monsters. They range in size from about the size of a one-man combat suit to the size of a large Buster Machine.
Space Monsters will probably be either statted out individually by a few types, or made as some sort of ridiculous template, I'm not sure. As for the Space Monster Expresses, they would be groups of multiple Swarms, each one representing 1,000 Space Monsters.
(Also, due to the nature of Buster Machine weaponry, I will probably allow normally single-target weapons to damage Space Monster swarms at a reduced rate, rather than not at all.)

The STMC
These massive alien beings originated from the center of the galaxy, with the sole purpose of erradicating humanity. They are the 'white blood cells' of the galaxy, seeking out dangerous infestations (like us) and destroying them. Also called Space Monsters (one species was long confused with the other) or Variable Gravity Wells, the smallest of these are the size of Buster Machines. The biggest rival the size of planets. These would be handled more like conventional D&D monsters, just on the Space scale.
STMC, by the way, stands for something so stupid that I'm not even going to repeat it here. It's a good way of differentiating them from the Space Monsters, though, so I'm using it anyway.


This is a project that I just got the idea for recently, and have barely started thinking out at this point. My next step is probably going to be to start statting out the various Buster Machine abilities, followed by a harder look at Space Monsters. Wish me luck!

[Kyace]

The Space layer barely notices humans and the like - HP, physical stats, and size categories are completely reworked to reflect the epic scale of Diebuster battles. A large conventional spacecraft might have about 30 HP, with planets sporting a couple thousand.
When the two layers try to overlap, a pair of simple rules can be used for interactions between them:
1: Any Normal scale being attacking any Space scale being inflicts no damage.
2: Any Space scale being attacking any Normal scale being kills in instantly.
Instead of handwaving interscale damage away, maybe you could set up a guideline to convert damage and HP in one scale to the other. Something like 20 normal scale HP is roughly equal to 1 Space scale HP. Or 50 normHP:1 spaceHP. All factions round down, and an attack can do zero damage interscale. That way when the very tough guy gets shot with the weak armored combat suit, it wouldn't hurt if he is only badly injured instead of instant croaking.

[ZebulonCrispi]

50:1 sounds like a good conversion level. That gives combat suits about 100-300 (~1d6) HP, a decent buster machine a few thousand (~100), and planets a couple hundred thousand. Good call.

For reference, the Combat Suits in question aren't just like a suit of armor, they're small mecha, like this (http://img.photobucket.com/albums/v26/professorscissors/snapshot20070402220125.jpg) (human in hand for comparison).

[ZebulonCrispi]

Well, shock and surprise, it turns out that completely revamping d20's rules is pretty darn hard!

Right now, I'm trying to throw together a system for the Buster Machines. I've got them divided into three classes (Melee, Projectile, Energy), each with its own Hit die, defense bonus, damage progression, and ability set, with the ability to pick one other type as a secondary and get a limited amount of abilities from it. The problem I'm running into is how to limit the use of Topless powers, a.k.a. Exotic Maneuver/Drive. In the series, it's quite evident that overuse of Exotic Maneuvers is physically exhausting, and I'm trying to think of a balanced, simple way to express that in game terms.

Beyond the Void suggested nonlethal damage to the pilot, but I'm not so sure about that one.
PRO:
1. It represents the concept of fatigue pretty well. Use powers too much and you go unconscious.
2. It naturally increases with level and constitution.
CON:
1. The massive increase in HP characters have between low and high levels means that either advanced Buster Machines will be able to use EMs nearly endlessly, or that I need to create a LOT of abilities that range widely in power level.
2. Related to #1, it makes choosing the cost of abilities that are useful at high *and* low levels very difficult.
3. I want Energy-type Buster Machines to be able to use EMs more than Melee or Projectile types. The only way to really do this is with some sort of bizarre Mental Hardness thing, which strikes me as an inelegant solution.
4. There's pretty much no way for pilots to take damage while inside their Buster Machines, so lowering HP is not dangerous at all. A pilot could burn through EMs until they were at 1 HP without fear, which seems contradictory to the spirit of the proposed system.

The other idea I'm toying with is to create a new gauge, call it Topless Points (I'd probably give it a better name later). TP is calculated as 5 + Level + CON modifier + CHA modifier.
PRO:
1. It doesn't spiral out of control like HP does, because it only goes up by 1-2 each level.
2. It accurately reflects the nature of the power, as something dependent both on physical stamina and force of personality (Effort and Guts!).
3. It gives me an easy way to affect the TP of Energy-type Buster Machines: just make it 1.5xLevel or 2xLevel instead of Level.
CON:
1. I really have no idea how hard this would be to balance, or how well it meshes with existing rules.

How does that sound? Is there some obvious way to do this that I'm overlooking that works perfectly?

Feedback is appreciated, thanks in advance.

[ZebulonCrispi]

Let's see how this looks.

Melee Buster
The Melee Buster is a Buster Machine built for one thing: Getting close to the enemy, and hitting it hard. It is sturdy, heavily armored, and is capable of unleashing massive amounts of damage at close range. The tradeoff for this power is a fairly meager level of Topless power, and generally limited long-range combat abilities.

Alignment
Any

Hit Die
d10

{table=head]Level|Damage|Special|Armor Class|Topless Points
1|1d6|Primary Ability|13|5
2|1d6|Secondary Ability|14|6
3|1d6|Primary Ability|14|7
4|1d8||15|8
5|1d8|Primary Ability, Secondary Ability|15|9
6|1d8||16|10
7|1d8|Primary Ability|16|11
8|1d10|Secondary Ability|17|12
9|1d10|Primary Ability|17|13
10|1d10||18|14
11|1d10|Primary Ability, Secondary Ability|18|15
12|2d6||19|16
13|2d6|Primary Ability|19|17
14|2d6|Secondary Ability|20|18
15|2d6|Primary Ability|20|19
16|2d8||21|20
17|2d8|Primary Ability, Secondary Ability|21|21
18|2d8||22|22
19|2d8|Primary Ability|22|23
20|2d10|Secondary Ability|23|24[/table]

Class Features

Topless Power
This Buster Machine's Topless Points are increased by the sum of the pilot's CON and CHA modifiers.

Pilot Skill
The Buster Machine's BAB, Saves, and Skills are all identical to those of the pilot.

Exotic Maneuvre
The pinnacle of a Buster Machine's strength is the power it draws from the will of its pilot. With the right pilot, an Exotic Maneuvre can turn a Space Monster swarm into a cloud of debris, push a mile-long spacecraft out of a gravity well, or even move entire worlds.
Every odd level, a Buster Machine gains an ability picked from either the Melee Buster Abilities or the Universal Abilities. These abilities can either be passive abilities, or powerful attacks that consume Topless Points to use.
In addition, at 2nd level and every 3 levels thereafter, the Buster Machine gains an ability from either the Universal Abilities, or from one other category picked at character creation.


Projectile Buster
The Projectile Buster excels in destroying enemies at a great distance. Its damage, armor, toughness, and Topless power are all average, but the Projectile Buster's greatest strength is that its basic attack is a ranged weapon (will hash out details on this later).

Alignment
Any

Hit Die
d8

{table=head]Level|Damage|Special|Armor Class|Topless Points
1|1d4|Primary Ability|11|6
2|1d4|Secondary Ability|12|7
3|1d4|Primary Ability|12|9
4|1d6||13|10
5|1d6|Primary Ability, Secondary Ability|13|12
6|1d6||13|13
7|1d6|Primary Ability|14|15
8|1d8|Secondary Ability|14|16
9|1d8|Primary Ability|15|18
10|1d8||15|19
11|1d8|Primary Ability, Secondary Ability|15|21
12|1d10||16|22
13|1d10|Primary Ability|16|24
14|1d10|Secondary Ability|17|25
15|1d10|Primary Ability|17|27
16|2d6||17|28
17|2d6|Primary Ability, Secondary Ability|18|30
18|2d6||18|31
19|2d6|Primary Ability|19|33
20|2d8|Secondary Ability|19|34[/table]

Class Features

Topless Power
This Buster Machine's Topless Points are increased by 1 1/2 times the sum of the pilot's CON and CHA modifiers.

Pilot Skill
The Buster Machine's BAB, Saves, and Skills are all identical to those of the pilot.

Exotic Maneuvre
The pinnacle of a Buster Machine's strength is the power it draws from the will of its pilot. With the right pilot, an Exotic Maneuvre can turn a Space Monster swarm into a cloud of debris, push a mile-long spacecraft out of a gravity well, or even move entire worlds.
Every odd level, a Buster Machine gains an ability picked from either the Projectile Buster Abilities or the Universal Abilities. These abilities can either be passive abilities, or powerful attacks that consume Topless Points to use.
In addition, at 2nd level and every 3 levels thereafter, the Buster Machine gains an ability from either the Universal Abilities, or from one other category picked at character creation.


Energy Buster
The Energy Buster is designed to most efficiently draw on the power of the pilot's Topless abilities. While its damage, armor, and toughness are all subpar, it has access to a wide variety of powerful Exotic Maneuvres.

Alignment
Any

Hit Die
d6

{table=head]Level|Damage|Special|Armor Class|Topless Points
1|1d4|Primary Ability|10|8
2|1d4|Secondary Ability|11|10
3|1d4|Primary Ability|11|12
4|1d4||11|14
5|1d6|Primary Ability, Secondary Ability|12|16
6|1d6||12|18
7|1d6|Primary Ability|12|20
8|1d6|Secondary Ability|13|22
9|1d6|Primary Ability|13|24
10|1d8||13|26
11|1d8|Primary Ability, Secondary Ability|14|28
12|1d8||14|30
13|1d8|Primary Ability|14|32
14|1d8|Secondary Ability|15|34
15|1d10|Primary Ability|15|36
16|1d10||15|38
17|1d10|Primary Ability, Secondary Ability|16|40
18|1d10||16|42
19|1d10|Primary Ability|16|44
20|2d6|Secondary Ability|17|46[/table]

Class Features

Topless Power
This Buster Machine's Topless Points are increased by 1 1/2 times the sum of the pilot's CON and CHA modifiers.

Pilot Skill
The Buster Machine's BAB, Saves, and Skills are all identical to those of the pilot.

Exotic Maneuvre
The pinnacle of a Buster Machine's strength is the power it draws from the will of its pilot. With the right pilot, an Exotic Maneuvre can turn a Space Monster swarm into a cloud of debris, push a mile-long spacecraft out of a gravity well, or even move entire worlds.
Every odd level, a Buster Machine gains an ability picked from either the Energy Buster Abilities or the Universal Abilities. These abilities can either be passive abilities, or powerful attacks that consume Topless Points to use.
In addition, at 2nd level and every 3 levels thereafter, the Buster Machine gains an ability from either the Universal Abilities, or from one other category picked at character creation.



This is far from complete, but it's a start. I need some other special class features beyond the abilities, and the projectile buster needs rules for its ranged attack. Beyond that, I need to actually make abilities for the four ability sets.