SO MANY GOOD SUGGESTIONS. :CCC

Well if you like FPS, maybe you oculd buy PAYDAY: Thei Heist? It's great game and fun CO-OP

Deus Ex and mainly Fallout 3 and NV are FPS RPG by the way, so if you don't like RPGs, they will seem less interesting to you.
As some already said, the Half Life series is a nice addition and you have to try Portal if you are a bit into puzzles.
In case you like your RPGs (non FPS ones) get a look at Dragon Age : Origins and Knights of the Old Republic (star wars), most of Bioware's games in fact.

Step 1: Look at my library and wishlist.

Step 2: Pick something.

That is all.

Steam Complete Pack, 72773913917505$ only.

Yeah, I just decided that I don't really want another FPS because I have so many I still haven't played.

Please suggest some really good platformers, though, if you know any. :x

Rayman Origin is a great game. Also you get Rayman 2 now when you prepurchase it ;)

Railworks + all DLC

Tell him to get Dungeon Defenders for you and him so you can play co-op, it's a good game

The possibilities are endless!!
How about a game with co-op in so that you can play with your friend?

tell him that best gift for you is to have friend like him ^_^

Saints row 3 :D
Edit: I love your pic :D

Just get your Rayman Origin!

Rayman Origins, it is bastly superior than Sonic Generations, also Rayman 2 with pre-purchase.

FORTIX

Anno or what's it called :3

This isn't a platformer or FPS, but how about Recettear: an Item Shop's Tale? It's a combo business sim (resource management strategy) and action RPG.

My dear pony friend, look for my advice: have no doubts and ask for Psychonauts.

QUBE?

Bastion (got that as a b-day gift and was happy... then played it, and was happier... then played it more, and was even happier (happiest?)).
Also, you seem to be missing Braid from your library for some reason. So either of those, but Bastion would probably have a larger $value over time.

Darksiders 2 Pre-Order!!!

Shank 2, Super Meat Boy, Dustforce, Sideway, (can be a hit or miss. I suggest trying to demo) Psychonauts

Cough cough Rayman 2 cough cough