Although a bit off-topic: I barely play games (besides an occassional 10
minute hack/rogue session ), but I have had a lot of fun playing
Darwinia the last few weeks. It is a really nicely done (commercial) game
that is a crossover between retro-classics and modern 3D strategy games.
And it works great on plain Slack without any extra libraries. Their site
is:

http://www.darwinia.co.uk/

The Linux demo installer is available under the downloads.

-- Daniel