catabyss.exe My first experience in a 3D FPS. One of the most memorable games I've ever played next to the original EGA mechwarrior. A good story, nice big map, and plenty of bad guys to incinerate with your fireballs makes this a fantastic addition for modern day especially for a properly configured tablet. ID made some great titles, but this was my favorite. Waiting for an Android port so I can play on my phone.
I spent many late nights playing this on a 486 DX4 100Mhz with a tiny 14" VGA monitor back in the mid 1990s. I would have rated it one of my all time favorites then, and haven't changed my mind now. If you have an old CRT that still works, use it while playing this game. It looks far better. Side note: Oh, and it's clunky at first, but once you get the hang of it, a JOYSTICK really makes this very fun.