I used to play this when I was a kid upon first release. I was dithering over the purchase for a few weeks but gave in and bought it the other day; I haven't put it down. It's still as awesome as it I remember it. Sometimes I i stop playing and ponder over how a game like this could be made so long back. Seriously, I love it.
Makes me crave Doom and Rise of the Triad. The latter I'm going to buy this very second, but the former is weirdly not available to purchase from GOG.