Continuing its adventures into Linux, Valve has released a penguin-friendly edition of another of its games, bringing the total to five. Could it be Left 4 Dead? Portal 2? HL2: Episode Two? Gosh, even Episode 3? Er, no, it's Counter-Strike: Condition Zero. Still, that's nice, isn't it?

Condition Zero added single-player to the CS world, facing off against snazzy bots. The development was a bit of a mess, started with Rogue Entertainment in 2000 then going to Gearbox, passed to Ritual Entertainment, and finally finished and released by Turtle Rock Studios in 2004. Yes, the gang who went on to create Left 4 Dead. The end result was a so-so mish-mash of scrapped, restarted, reworked and remade content, but shooting men is generally fun.

CZ joins Half-Life, Counter-Strike, Counter-Strike: Source, and Team Fortress 2 on Linux. If you've already bought the games for Windows or Mac, you now have the Linux version free too.

Valve says it's releasing Linux editions of more of its games "in the coming weeks and months." Good things come to those who wait. Valve's looking to get prototypes of its 'Steam Box' living room PCs--expected to have Linux as at least an option--into people's hands in 3-4 months, so the more Linux games the merrier. Steam now stocks 80 Linux games in total.