Interesting concept of sort of Space-Invaders with additional tasks (i.e., destroying the pylons). I think you could pull a lot more out of this idea and make a good little game from it. The trail effects on the Bypassers are really quite good. The gameplay is slow, as others stated, which isn't always a bad thing - though by the time I was able to upgrade mana, I was already constantly needing to use mana to keep mooks at bay. The only way I upgraded was by purposely letting them hit me.
Hopefully you keep working on this sort of thing - the art and atmosphere is top-notch and the upgrades were interesting.