homebrew-draft-01.txt

Character Creation

Choose an ideal:
  - Attacker (+2 when attacking)
  - Defender (+2 when defending)
  - Healer (+2 when healing)

Choose a form:
  - Tanacity (disability resistance)
  - Midrange (extra healing from others)
  - Bulky (extra damage shield)

Knowing these two options, you can design your character's aesthetics to match. The bonuses granted are explained below.

The (In-)Human Body

Your body is divided into four parts:
  - Head
  - Arms
  - Legs
  - Core

Each body part has multiple damage levels:
  - None (the default starting value)
  - Minor
  - Moderate
  - Major

When you take damage, you increase the damage level of one part (chosen by the GM) by one, up to the maximum. If a part reaches the maximum, then it is considered disabled.

The core cannot take damage, unless at least one other body part is disabled. If your core becomes disabled, you are knocked out.

If your form is Bulky, you have an extra damage shield around you. The shield is the first body part to take damage and the last to be healed.

Lucky Break

At the beginning of the game, you receive two luck points - you gain more luck points for doing something impressive (dramatic roleplay, clever ideas, rule of cool, etc.), and you can spend one luck point to reroll a failed action (see below), but only once. You can have at most three luck points.

Rolling To Act

When you want to take an action (attacking, defending, healing, or otherwise), you must first determine the difficulty of said action, thus the target number. Some common targets are Easy (5), Medium (10), or Hard (15).

Roll a d20, adding the bonus granted by your ideal, if appropriate. If you match or exceed the target, your action is successful.

If the body part you are trying to use is disabled, when you roll a d20, instead roll two d20 and take the lowest result. You usually use your head for sensing, arms for combat or interacting, and legs for movement.

If you have the Tanacity form, and the body part being used is the only disabled body part, you may ignore the roll-two-take-the-lowest rule in the previous paragraph.

Healing

When acting, you may choose to heal one of your body parts by one level, or a nearby ally's body part by up to two levels. If the target of the healing had the Midrange form, they gain one extra level of healing. If a body part is healed to it's lowest damage level, you can allocate the remaining healing to another body part.

If the core is damaged, it must be healed first. If the target of a healing action has a damage shield (such as from the Bulky form), it must be healed last.

When using the healing action, the difficulty is Medium (10), unless specified by the GM.

Appendix: Leave Luck To Heaven

When rolling a d20 with an optional reroll, it's useful to know the mathematics behind the chances of success.

W: Chance of success from one roll
L: Chance of failure from one roll
W': Chance of success, w/ reroll available

W + (LW) = W'

Given the chances of Easy, Medium and Hard targets, here are the possible outcomes of any one action.

Easy: 5+, 80% or 96%
Medium: 10+, 55% or 79.75%
Hard: 15+, 30% or 51%

Working:
0.8 + (0.2 * 0.8) = 0.96
0.55 + (0.45 * 0.55) = 0.7975
0.3 + (0.7 * 0.3) = 0.51

Appendix: Theory and Practice

This ruleset is based on the ad-hoc system my D&D group has started using when one of us can't make it, and we resort to a one-shot. It's based, at least partially, on a ruleset from a big book called "Index Card RPG", as well as other house rules that have been used for some time. I must admit, I haven't read that book, I'm only running off what my DM has said about it.

Some parts of this system are lop-sided, like the disabled mechanic being 5e's disadvantage system, but lacking the advantage equivalent. We can occasionally buy advantage with inspiration (here called luck points), but mathematically, purchasing advantage is worse value than having a reroll available - this will need some thinking.

It's interesting to note that the players are the ones making all of the roles, and those roles are, for the most part, tipped in the player's favour.

There are many possible options available for development, such as having different body parts for each arm and each leg, and other small adjustments to allow any kind of setting or set of abilities. While my group uses classes as shorthand, I've deliberately left them out of this, because I think classes could be laid on top fairly easily, based on setting.

Finally, this text is super dry, because it's still a prototype - examples and prose come later.

Feedback welcome, and appreciated!