Heya,
Fallout 3 is a fantastic game. You can play it a few times too, as it has different ways of accomplishing things and you can be a different character. The first time I played, I tried to save everything and everyone. It was fun. But I had even more delicious fun by playing through again with some specific handicaps and requirements to make it harder, and for me, more fun. For example, I went with melee and small guns the second time through, with high levels of sneak, and less worry about dialog and tech and all that. A sneaky bruiser. I had a lot of fun trying to get my karma as low as possible. The titles and images in your pip to display your horrible karma is hilarious and really fun. I mean, the first moment of the game, instead of saving the bully's mom, I took her down with a baseball bat, killed the radroaches, and then went out and killed the bully and took his clothes and pocket knife. It was so damn satisfying.
GTA4 is probably a great game. But it depends what you want to do. All the GTA's play the same. I still think GTA1 was better than the rest, just because I had so much more fun with that top view and driving around. Unfortunately there's a lot of problems with GTA4 on the PC. It's a really bad port apparently and while the game is great, it just doesn't work properly and is gimped. So due to that alone, I would recommend against buying it for PC.
Mass Effect was an awesome, awesome game. If you want something new, that game is it. Great story, great graphics, great game play. You could play it several times (lots of methods to accomplish things), but ultimately the story wouldn't be different.
Note that in Fallout (all of them), the ending is different based on what you do. So each time you play, so long as you did different things, the ending/conclusion to the story changed.
If you want an FPS, check out Left4Dead so long as you're willing to play with real people online; single player will leave you somewhat wanting. Even TeamFortress2 is a fantastic game for this (and still looks great).
If you want an RPG, Fallout3 is really great for it (while combining a lot of elements of FPS/3rd person).
If you want a survival horror game, DeadSpace is a treat, a real gem. Especially if you have a great audio setup (this game has the best audio experience a game can offer, ever). It's a 3rd person stomp out in space. Really fun, can be really hard at times, and is beautiful. Again, great audio. Play in the dark, it's the only way, and turn up the volume!
Cheers,
Facebook
Twitter
Instagram