I am one of the developers of a game called TagPro. It's a team based capture the flag game with an incredibly simple premise, but surprisingly deep strategy. We have 184,772 registered players, and probably 10x that count of unregistered players. Real simple to drop in, play a 5-10 minute game using only 4 keys, and get back to whatever you were doing.
Thanks! I was a big Subspace/Continuum player up until about 5 years ago. Mostly played on Trench Wars in the continuum days. The skills are surprisingly transferrable to TagPro.