Eve-Online already does this; the speed your ship is moving determins the likelyhood an explosion will even make an impact. You can speed-tank some ships, as opposed to armor and shields.
Granted, its not physics itself, just a simple math equation, but it counts...
As for ranges, I use Blasters and drones for <10k ranges, and Cruse Missles for >150K ranges (and run like hell if anything else gets in between...)
Plus, everyone (except the communists in China :P) are on the same server, which is kinda cool really.
Now with 100% more factional warfare!