I was just flicking through the pages of abandonia.com and what do i see...
http://www.abandonia.com/games/en/346/MDK(MurderDeathKill).htm
Quite possibly my favourite game of all time, free :D
Theres also lemmings, cannon fodder, doom2, civ2, GTA, and the original descent :D
They have Quarantine (http://www.abandonia.com/games/146/download/Quarantine.htm). I used to waste so much time playing this game, but it was just so good.
Heh, I remember when mdk came out and I was like man, I wish my pc could run that :(
They have Street Rod too, the crappiest, but also most brillianty entertaining game of my youth 8)
btw:
mdk install directory has to be in the root in c: to run.