There are some Metroidvanias out there with pretty big graphics that are very playable with a keyboard.

LaMulana comes to mind. There is text but it is a pretty good sized font and all the characters/objects are somewhat large, easy to see.

Here you go!

http://www.unstoppablegamer.com/category/accessible-game-reviews/

Platformers

OP said no platformers. Also OP the link I gave you is for a website for gamers with disabilities. Also Bump.

How about some older turn based RPGs? Might and Magic 1-5, Ultima, Bard's Tale, Wizardy and the like?

The Ur-Quan Masters are controlled solely by keyboard and got loads of exploration. It does have fixed font, though, but it's plenty big!

http://sc2.sourceforge.net/

Have you considered a controller? I wasn't a fan of them until I got an Xbox 360 controller. I don't use it to often even now, but it's decent enough for most games. Then you can give the Witcher games another go :).

Only keyboard? First thing that comes to mind : Tomb Raider
The 1st one has aged a bit poorly perhaps, but the 2nd is much better and the 3rd the best. And being Tomb Raider, all of these games have fantastic exploration and interesting stories.

Apart from that Race the Sun is an excellent racer that is a lot of fun in short bursts.
Pshyconauts I think is another good option. I'm pretty sure it is easily playable without a mouse, and it has a great story, characters and fun exploration. But it is a bit platformy though.

If you can get your hands on an xbox360 controller (though possibly other will work as well) and want something better than all of the preceding combined : Outcast

10 feet away... what size is your screen?

Its my living room tv, 55"

Crashlands.

Two Worlds may be OK, I do play it with mouse/trackball & keyboard instead of touchpad + keyboard, but I don't care for touchpad. Story is light but the sandboxy exploration is good.