Games like TRine 1+2

For co-op fun, the first thing that comes in my mind is the little big planet platform games, but those unfortunately were only on playstation console. Played countless hours with my sister and bro. Still worth it though could play them again, since also infinite co-op levels made by community.

Also maybe try ibb and obb. And maybe Portal 2 if you both like puzzles ??

Maybe Battleblock Theater? It's a humorous platformer that also has local coop although it doesn't have riddles like trine does, but still requires cooperation to progress

Giana Sisters Twisted Dreams
Party of Sin

Final Exam

The Cave.

Castle Crasher is awesome
Never Alone
Forced
How to survive
Porcunipine

It is not very simliar to Trine but Guacamelee is great. It has local coop and good humor.
Maybe you will like it :)

thanks for all the suggestions

Try Rayman Origins or Rayman Legends. I had a lot of fun in their coop mode.

Gauntlet The Dark Legacy is like Trine in which you are playing it with 3 other friends and you go around and "kind of" solve puzzles. Its just a really fun co op game and there are some puzzle mechanics added.

The Binding of Isaac Rebirth has coop.

Edit: Oh, you're looking for games similar to Trine. Well, all that I could think of have already been pointed out by others, but I'll leave this suggestion here anyways =)

Full Mojo Rampage and Don't starve together are both excellent randomly generated map-based co-op games.
Nothing like Trine, but if that's something you wanna explore..

Capsized (currently 80% off in the Steam Store). It has somewhat of a Trine like vibe to it with its environment :-)

http://store.steampowered.com/app/95300/

Torchlight 2 has co-op, unfortunately, as far as I know the 1st one doesn't. Other than that, most of the games suggested above would be my picks too.

Or get a WiiU and half of the Nintendo library.
Battleblock Theatre is a nice choice if you just want to try one.

Well, it was compared a lot to The Lost Vikings 1-2 by critics.

Skyrim. You just have to find the proper mod, I'm sure it exists.
Apart from that, Steam has a cool feature (that you have to check manually because some recommendations have nothing to do with the original game) http://store.steampowered.com/recommended/morelike/app/35700/

Lovers in a Dangerous Spacetime...I thought that this would just be dumb, but ended up loving this as a co-op game. It's truly a great game.

And yep, I own (and love) Trine 1&2 as well.

Holy necro bananza. Well while we're here, it's a shame Trine 3 ended up being so absolutely atrocious. 1 and 2 were some of the most fun co-op experiences I've ever had, absolute masterpieces.