Nice, its a very original idea, the concept of being an "antivirus", and defending the operative system, and trying to delete the viruses, like the spider ware, or the pumpkin.exe, i loved it, the mechanics are intuitive and its funny to play, really enjoyable, BUT, personally I hate the turrets, I think they make contrast to the other enemies, because to defeat the other enemies you need to be fast, but with the turret no, I find it boring, but its cool to have a big enemies variety.
I like the TRON style, THE GRID, but in pixel art looks good, i like the movement and animations of move, the atmosphere with the [press enter to login], its simple cool!
Maybe the boss is hard to beat (I can't), but the boss battle is cool!
(I'm sorry if my English is bad, I speak Spanish)