Teleglitch is amazing, a must have for any diehard gamer. It's brutally hard, I still haven't been able to get to level 7 yet (I probably need to use to learn the knife better), but you rarely feel cheated from your many, many deaths. Like Nethack, all your problems could have been avoided in hindsight.
The graphics of the game, while extremely rudimentary, actually add to it; I love how much horror shows through, even though the monsters and worlds are just a few blurry pixels. The storyline is interesting, and vividly describes the terror of the world you're living in, with a touch of humor as well. If you're not interested in reading the computer logs to know how things got they way they are, they're also completely avoidable, and never forced upon you.
All of the monsters have their own unique personality (and freaking TRICKY movement patterns! Those stupid small ones, yeeeeeaarrrgghhh!), and none of them seem repetitious, or rehashes of earlier versions.
The best part about this game? THE CRAFTING SYSTEM! Holy heck, I wish EVERY crafting game was as intuitive as Teleglitch. Instead of needing a wiki article explaining how to make things you'd never have known exist, all you do is press a single key, and the crafting meny pops up, showing your entire inventory, what can currently be crafted from it, and what each of those items will cost you, using an easy to follow line diagram system. Crafting is so easy, it can be done on the fly, during fights! It couldn't be improved upon, except possibly to see items you can't craft yet, so you know what they take, but IMO, that would take away from the fun of discovery in the game, and add very little.
Teleglitch is a game I'll always be happy to own, and if I had somehow pirated it (why? it's SO cheap!), I would actually pay money for a retail copy to support the designers. I collect games like they're little works of art, and am proud to display this in my collection.