I purchased Magicka today, and I am quite impressed with it so far. It is an action RPG title for $10, and the gameplay reminds me of Nox a lot. You control a wizard, and you mix spell elements on the fly to cast different spells. Experimentation is key, and then you also unlock certain more powerful spells via exploration. You swap out what staff you are using as you play, and if you, say, fly off a cliff, that staff is gone forever.
The game is definitely indie, and needs polish. The spells look fantastic, but the world is of a lower grade. There are a lot of bugs (I haven't run into any major ones yet, but some are having crash issues). There is nothing like trying to cast a fireball, though, and accidently placing land mines right infront of you! The game forces you to play with 100% friendly fire on, so if you play Co-op (it supports up to 4), it can be a messy affair.
There is the main story mode, which I'm guessing you could blow through pretty quick once you know what you're doing, but if you are like me you will find infinite ways to freeze and zap yourself to death. There is also a survivor, last stand mode that is geared to more hardcore players. I have yet to try it out.
Check out the gameplay here: http://www.youtube.com/watch?v=8ZRzkWmVpEQ