I do believe you can get torchlight 2 to run lan, I've read you can even do that with 1 copy but don't quote me on that.

It isn't an Indie game and it's fairly old, but Starcraft 1 needed only one CD. Basically, you could install the full game on one PC, and the multiplayer only client on all other PCs. As long as the player with the full install was playing, there were no issues.

Most recent games either avoid LAN (sadly) or somehow try to rope you into buying a second copy (for instance, through horrible, horrible DRM checks). Still, there's bound to be a few games out there which both of you can enjoy.

I would help though if you told us what genres you're interested in. It's easier to make good suggestions if we know what you're looking for. :)

For PC I'm not sure, Lego batman has local co-op, i'd look into all the lego games for that. If you have a console then that opens it up quite a bit.

I am interested in all sorts of games even when I am not good at them like FPS games, my fiance on the other hand like 2D games a lot better. We both are big fans of Terraria and feel like game with easier controls would be better for her. She is getting better at using a mouse and keyboard when attempting to play first person games. Trying to get her to play through Portal. The consoles that we have is an orginal Xbox and a Wii.

The Wii has a few good games, you just have to look for them. I hear new super mario bros is pretty good, that'd fit the 2d bill pretty well and easily accessable to anyone. I still stand by the lego series comment too, easy fun play style.

Just browsed through your library and i noticed you got Trine and Shank.
Both are 2d and you can play both in a hot-seat session if i remember correctly

Volfied is an old dos-game which was hot-seat multiplayer. You will need DOS-Box though. Controls are horribly simple, but the game can be quite difficult. May be a fun way to pass the time

Super Meatboy is also an option. Challenging, up to the point of frustration and not "truly" multiplayer, but still fun to play together. I once played the game with a friend. We basically took turns. Works well enough. :)

Age of Wonders II (and the expansion) can also be played multiplayer on the same PC (hot-seat). It's a bit like Heroes of Might & Magic. Very tactical, may not be your cup of tea at all. Early difficulty may be a bit challenging though.

If I think of other ones as well, I'll be sure to post suggestions here. :)

Awesomenauts would definitely be worth a try, great DOTA style game played in 2D, featuring local co-op

castle crashers (quasi-2d sidescroller) was decent co-op on xbox live and assumingly on PC. Very simple control schematics regardless of platform. Pretty much a hack-and-slash action (super lite-rpg).

I played it on xbox with my wife. If you want to shoot people co-op on xbox then halo or rainbow six vegas were fun co-op fps experiences for us (in rainbow six:vegas we even looked like our real life counterparts from taking pics of us webcam). Lots of fun.. best way to strengthen a relationship imo. Gears of War also good co-op play (all from the comfort of sitting next to eachother on couch or via system-link in other rooms).

and, of course if you enjoyed terraria together - maybe first person minecraft via PC or local co-op xbox couch play. fun casual games... anyway, have fun!

BROFORCE. Although it is still in early development, its great fun. With destructible terrain and 80s and 90s action hero parodies, this is a great great game. And it even plays better in local co-op.
Check it out in greenlight.

Dead Pixels. If you like retro zombie mayham than you'll drool over this game. The local co-op is the bonus that puts this game over the edge.

Rayman Origins - Passed full game in co-op with my wife. Now looking for something similar! Strongly suggested!

HAMMERWATCH! http://gtm.you1.cn/sharedfiles/filedetails/?id=122788084

Really hope this gets greenlighted.