Take a d12 die and weight it as such:
{Human, Human, Human, Human, Human, Orc, Orc, Orc, Orc, Elf, Elf, Elf}
That's a 5/12 change of rolling Human, a 4/12 chance of rolling Orc, and a 3/12 chance of rolling Elf.
OK, I think you know where this is going.
Health stats are as follows:
Human = 12
Orc = 15
Elf = 20
In a PlayerA vs PlayerB battle, PlayerA rolls the weighted die and scores a hit if the result depicts PlayerA's race. Any result other than PlayerA's race is a miss. PlayerB takes damage by losing one health per hit.
Example:
PlayerA is Human (ie: health=12)
PlayerB is Elf (ie: health=20)
PlayerA has a higher chance to hit PlayerB, however PlayerB starts with more health.
I've not run this through a simulation yet, but the odds should match up where each race is equal.
I suppose this Rock, Paper, Scissor example could have been played using a d6 as well. Weight the d6 as follows:
{Human, Human, Human, Orc, Orc, Elf}
And assign starting health as:
Human = 10
Orc = 15
Elf = 30
The rules apply as before. Player rolls die and scores a hit on the opponent if result is Player's race.
The d12 example is slightly nicer in that the starting health for all three races are closer in value.
Game progression may be slow when using a single die per turn. The probabilities of a hit are only 1/2, 1/3, and 1/6. My thinking is that the game should scale to using multiple dice per turn (ie: roll 3 dice to do damage 0-3).