#2
The concept takes about eight seconds to explain: you are a lightcycle, you leave a wall behind you, you try to make other people crash into it. Everyone gets it immediately, which matters more than people think when you are trying to get six people playing at once. I first came across this in the same era I was playing Red Alert 2 and Unreal Tournament, and it has the same quality those games had: the rules are simple enough that a newcomer can contribute in round one, but the ceiling for how good you can get is surprisingly high. Runs on anything. No accounts. No launcher. It just works.