Wyv and Keep is a great puzzle platformer with a few twists. It's important to note that this might look a bit like games such as Spelunky. While the theme is similar, the gameplay isn't. Basically you control the two treasure hunters - either alone or in coop with a friend. You'll have to avoid enemies and traps rather than fighting or destroying them.
The goal sounds simple: Reach the exit door. However, it's typically not that easy. You'll have to avoid pits, traps, and enemies, while also triggering buttons, moving boxes, etc. Some things can only be solved involving team work. For example, one character might have to fill a gap in the ground, while the other pushes a box over. On another map a wall might be too high, so you'll have to move a box, jump on it, and then use your friend as a stepping stone.
I've been playing this game since its initial Desura release and it can be lots and lots of fun. The game's pixel art is well made and tries to emulate late 16 bit era games (i.e. Super Nintendo and other 2D consoles). Some parts of the game are higher resolution though. If you're not a fan of pixelated game and prefer HD graphics, better skip this game.
The game offers replayability through challenges: Beat a level as fast as possible, beat it with as few retries as possible, and try to collect as much money as you can. Also, the old Desura release had its own level editor. Accordin to the devs (see comments under this review) the editor will return once Steamworks integration is working/complete.