I played the first level twice, got swarmed by a hoard of skellys.
First impressions, feedback and suggestions:
I couldn't use the spell wheel at all, my keyboard doesn't have function keys and trying to click on the icon with the mouse while something's rushing towards you felt clunky.
It's kind of annoying that the projectiles you fire are so slow, as enemies can walk out of the way, and you can't lead them because you have to click the enemy to fire at them.
Items that you can pick up could always have the outline effect applied, they're easy to miss and walls can obscure things easily.
Enemies that you have line of sight to could have their outline on if they're obscured by a wall, currently they only have it if your mouse is over them. You can be in the same room as an enemy and not see them because you're not close enough to a wall to make it fade out.
Moving, interacting with objects and attacking an enemy are all left mouse actions, so if there are enemies clustered in a doorway and you're trying to shoot at them, if you click on the open door your character will start walking towards it to interact instead of shooting at the enemies. I'd suggest either having another interact control or not making the player walk to a distant object to activate it, only activate if they're in range.
Walls fading out can make it hard to distinguish where the boundaries of rooms are because the floor texture continues uninterrupted underneath. I'd suggest having a shadeless black object at the bottom of each wall piece which isn't affected by the transparency shader, then where the player can walk should be much clearer.
It'd be nice to access the keybind menu during a game session. I wanted to check the controls again after starting and I couldn't. Also rebinding would be good to have.
All in all, impressive, very nice.