The idea of the portals is really cool, but i think it could be improved on a little bit, since i found that it was rather easy staying alive if i just stood still at the top of the level, as the enemies would just fall down to the bottom, if the enemies or enemies's projectiles passed the portals that would make the game a little bit more challenging, also there's no way of keeping your score, a timer would have felt nice, the idea is really good, the music is good. good game.