Questions for my game design (based on erfworld)

[tomaO2]

Hi, I'm making my own game from the Erfworld universe. A lot of it got lost during the website lockdown, but I've reclaimed a portion of what I lost and I'm looking at various aspects.

Link here for anyone looking to see what what I have so far.
https://forums.spacebattles.com/threads/remnants-of-the-toma-erfworld-rpg.719815/
I posted that link before and didn't get much feedback. This time, instead of asking for general comments, I'm going to simply try asking specific questions to help me refine my system.

My first question is on size modifiers. Units have various stats. Combat, defense, hits, move, etc. Bigger units have more of everything, but I have been trying to include size modifiers as well. This is my current method.

There are 6 sizes in my system. Massive (-7), huge (-4), large (-2), medium (0), small (+1), and tiny (+3).

Current idea for doing a combat roll is this.
Attacker rolls 1d20, plus combat stat and modifiers.
Defender rolls 1d20, plus defense stat, and modifiers.

Alternatively, I could try to make it a single 1d20 roll, where 1-10 succeeds, and 11-20 fail, and total the positive modifiers of both units against each other. So if attacker has a +3, and defender unit has a +2, then the attacker gets a +1 bonus and can hit on a 11 or less.

One of these modifiers is size. It works in a sliding scale, not a static number.

It works like this, a large unit has a -2 size modifier to defense.

A medium unit attacks, the large unit has a -2 to defense.
If a small unit attacks a large, the large unit has a -3 to defense.
If a large unit attacks a large unit though, there is no modifier.

I wonder if this adds an unneeded complication to the calculations. It seems like other systems give a straight modifier for everything. A -2 modifier for a large unit is -2, regardless of what size unit it fights. Should I be doing that instead? Should the size modifier count when both attacking and defending? Maybe something different?

[aimlessPolymath]

On 1d20 + your mods- enemy mods vs. 10 compared to 1d20+mods vs. 1d20+mods:
The first one is somewhat more consistent, with each point of modifier representing a hard 5% swing, while in the second, each point of modifier is 5% or less, with each cumulative point of difference between two modifiers representing a smaller and smaller change in probability in success. This is honestly a pretty minor point; I don't think it really makes a difference.

Size modifiers:
As far as I know, 3.5/Pathfinder (the systems I know of with size modifiers) have a single size modifier, but it's applied to both attack and defence rolls; as a result, Large attacking Large has a -1 to the attack roll, but also a -1 to defense, cancelling out. Based on your examples, it seems like that's what you're doing, though, so I'm not really sure I understand your question.

[tomaO2]

I guess I was kinda wondering the idea of size modifiers to begin with. Like, does it make sense that you get a positive/negative modifier to size when both units are the same size? My initial thought was no, but then I was looking on some systems and it seems like there is a permanent modifier that isn't subject to the opponent. So I was asking about that aspect, and if I should switch to that sort of model, or try something different.

When I last tried combat, it was a clunky system that took a long time to work through the rolls, and I was thinking maybe I was overcomplicating this for players. One area that seems excessive is having them do a sliding scale of of hit chance depending on exact size difference.

One of the big differences in the game I'm creating, as opposed to a traditional RPG structure, is that hit points/damage is largely static. Leveling gives a minor bonus, at best. I'm really interested in size mattering for combat, I also am working on differences in damage dealt, such as units that are two sizes larger than the target automatically crit, and units that are 4 sizes larger don't really roll to hit anymore, because they do area damage that the defending unit can't escape from before it hits.

In short, I'm asking, what is a good way to handle size modifiers. Is my current system fine or should I do it different?

In erfworld, 8 groups are considered the ideal (16 if riders on mounts), so the general target would be two players, each with an 8 stack of units to fight each other when doing small group combat. I'm currently trying to make a system to efficiently handle groups of around, and then make a second one for armies.


Edit:
This isn't going too well...
Link to my ruleset. I recently managed to get a copy of it and am posting it on Spacebattles.
https://forums.spacebattles.com/threads/toma-erfworld-rpg.719815/reader/