One Must Fall 2097. Still do (in Dosbox). Excellent concept, could use remakes and clones.
And now
free too ;p
A FlashBack-like whose name I'm blanking on (starts in jungle, hero dropping from a parachute stuck in trees)
DarkStone. An
excellent Diablo-like hack-and-slash game, much better than Diablo, and a match to even Diablo 2. As its studio is totally dead now, the community plays it unrestricted (complete abandonware)