42's Orb of Valhalla is a tile matching game which is a cross between Dungeon Raid and 10,000,000 (both of which are great games). You need to match tiles in the same way that you do in Dungeon Raid. You receive non-linear rewards for larger matches. Like 10,000,000 the block matching effects what goes on in the dungeon at the top. Unlike 10,000,000 (but like Dungeon Raid), there are also enemies that appear in the blocks. You also gain karma (in various ways while playing) which you use to improve your abilities in future games. It's very easy to play (my wife isn't a gamer, but she loves to play it). However, for those who want depth, I'm working hard to add as much strategy to the game as possible. I can easily travel twice as far in the game as my wife. Working to create large tile matches, focusing on maximizing gold or brains, choosing the right spells and upgrades, loading out the player with the right spells, etc., all have a big effect on how far you can get.
Another strategic aspect of the game is to choose the spells that will be available to you in-game.