Hmm, this game is playable on Chrome, but despite the assurance that defeating all the enemies is not needed to finish each level, I found that not to be the case, especially in levels 2 & 3 (I gave up after I died at level 3, having taken a number of tries to even get past level 2 to begin with :p); oftentimes I would find 2 black holes near an enemy, only AFTER I have defeated said enemy (:
The black hole mechanic was interesting, although the reflected light of your bullets bouncing against the wall helps as well :)
Perhaps this is not a game for those with twitchy fingers or those predisposed to making mistakes long and plenty, but the idea behind the game is quite neat in of itself, so good job :)