Duke Nukem 3d suped up (eDuke32)
I'd been trying to get DN3d working OK under Windows XP using Dosbox and XP's own compatability settings but with no real joy. Then I stumbled across this! It's great! Yes the not-true-3d aliens can look a bit silly at certain angles BUT the gameplay makes up for it. It runs so well and you can tweak it up to something quite tolerable. Go on... have a dabble.