We've being doing health and damage in terms of blocky blocks.

While I principle I like this, it makes for ugly-assed scaling, and the size table makes it worse.

HERE'S AN IDEA .. races have scalars representing their size. All you have to do is match scalars to make them compatible in a fight.

This affects combat damage and attack bonus/penalties by multiplying and dividing.

My weapon does 10 damage, but I'm size 10. You're size 100. So my weapon does 100/size 10 = 10 damage. Weapon damages and size calculations can be precalc'ed quickly before combat. For ease of use, if you're in a "bigger" or "smaller" world, you should scale your values to match. Similarly, if an alien comes to your world that is smaller or bigger relative to him, he should scale his values to match.