Valve has originally ported their original Half-Life title to Linux.
For those owners of the original Half-Life, it's time to fire-up Steam. Valve today released a native Linux port of the original Half-Life game. Yes, the game originally released in 1998.
If you didn't buy the game a decade ago, Valve still sells Half-Life on Steam for a price of $9.99. The Linux port of this game, which is powered by the "GoldSrc" engine (a heavily-modified Quake engine), is currently considered beta.