It's an RPG set in a post-apocalyptic wasteland after the world has been destroyed by nuclear war. You set up your initial character with a fairly conventional set of RPG stats, plus a set of skills that you'll use as you play. Some of these are combat skills, like conventional or futuristic energy weapons; some of these are thief skills, like sneaking and lockpicking; and some of them are just complete bullshit that do nothing, to punish you for not using a guide.

As you progress through the game, you'll meet other characters that you might want to recruit into your party. Some of them are much more useful than others. It is a good idea not to hand them automatic weapons, as they'll squander all your precious ammunition on the first rat that they see. There are a lot of random enemy encounters.

There's a technologically advanced group who cling to the remnants of civilisation, who you can grab some very decent gear from if you play your cards right. The final boss is part of the children of the citadel, a cult that has sprung up in the wasteland. He has plans to convert humanity into a new hybrid species to better cope with the world after the nuclear war. You cap his ass.

Although it was a very influential RPG in its day, certain aspects of it - the UI, more than anything - have aged really badly. The plot still holds up, though, and it's a lot of fun to play if you can push past the jank.