One of the best games on the site. However, I'm pretty sure that there are some people who could kill for as much as an idea of getting a cow into the mothership with help of granades only. And I don't mean vegetarians.
In my humble opinion, after 5 hours of trying to beat a level, you should be able to collect a powerup enabling you to bounce of the walls :P
I cannot understand how a game which gave my a headache, kept me playing it for so long^^