Loved the music at the very beginning!
The concept is very cool and, once one gets the hang of the core mechanic, the game becomes increasingly more fun with each level.
If the Tab key could be used to switch views back and forth, and if there was a clearer indication that the icons are actually the gray blocks seen by Viruz, the whole experience would've been even better!
Swapping between the two views was exhilarating on the last couple of levels. Jack & Viruz it's definitely challenging but fair :)