The game goes slower and slower as enemies arrive.
It looks funny though :( I would have enjoyed to be able to rate your game !

Painfully slow; as Kushulain said, seems to be tied to the number of dynamic objects being drawn.

Even if it were running at a much faster speed, though, it felt impossible to be able to reach and shoot down all enemies, given the speed of the player unit relative to the speed of the enemies. I spent my first $80 on a movement upgrade, hoping that it would carry over from one game to the next, but it doesn't appear to do so. That would be one way give the player a chance, though they would have to suffer through a lot of losses without giving up for that to work.

As said earlier by Kushlain, i can't kill 2 enemies in a row because of the speed, who goes slower on time.

Nice concept yet the pace is very very slow.

idem (slower) :-( , I like the background music

It was too slow to play at all on my laptop. Shame, it looked really promising :(

Really slow, but nice gameplay. Love the menu/upgrades. Good job! =)