The graphics have certainly not aged well and the controls do take some getting used to, but the game is mindless fun. Its a diversion and can be a guilty pleasure. There is certainly no real plot to get hooked into and the game relies primarily on its mindless and over the top civilian violence. You've probably spent more on worse. If you're looking for something to play in between bigger games, you can't really go wrong with Postal.
It doesn't matter what you've played before, play Freespace 2. This game redefined the genre. The graphics are still strong, there's a bunch of mods, the story is great, the combat is varied and the differences in scale between small fighter ships and capital ships is incredible. I can go on at great length and break things down but it all comes down to this: BUY THE GAME.
Die By The Sword is a game that has aged badly. There are definitely control issues and the graphics are tough to look at in today's day and age, but its a fun game more than worth the price of admission. Chopping off limbs is fun and beating someone to death with their own severed arm never gets old. Worth a look.
Giants is without a doubt one of the best Interplay or anyone else has ever put out. The game features three unique races with three unique playstyles, plenty of artistic style, humour and tight controls. The graphics hold up fairly well and this is a game you'll WANT to tell your friends about. This is the best place to pick it up to with full XP compatibility. Do yourself a favour and pick this one up today.
Freespace is only outdone by its sequel Freespace 2. If you want some incredible space sim action with an incredible storyline and some pretty amazing graphics that hold well even today. You can't go wrong with Freespace. The missions are varied, there are plenty of ships and weapons to work with and the sense of scale is impressive. If you thought games like X2 or Tachyon had scale, you can thank Freespace for pioneering it. You'd be missing out on one of the best of all time if you didn't pick this one up.
After the excellence that was Descent 2, its hard for anyone to follow it up. Descent 3 however was able to recapture most of the magic while bringing it up to date in the graphics department. This is one of those game that, arguably, cannot be compared to anything else. Superb graphics at the time, unmatched true 3D gameplay and some devilish level design make this one of the Interplay classics that everyone should experience.