So I've seen on some games that whenever you attack another person, a little number will pop up on the person you are attacking showing how much damage you're doing to them.

I was curious as to how this is done?
With overlays, mostly.

Spuzzum's s_damage library can also be used.
In response to Foomer
So you have to make the numbers graphically?
In response to GohanIdz
BYOND doesn't support anything except graphics on the map.
In response to Foomer
Ah, gracias.