Too hard, I have some advice to make it easier.
I'm using the trackpad on my laptop and the game is extremely difficult. You should have the left and right arrow keys controlling the direction and have the space button fire the slingshot. Keep the QWEASD keys for the cats and everything else the same and you'll have a fun yet easier game.
Very fun.
However, I think there should be a continue, or at least a way to continue later.
Good.
Initially, yes, this game is pretty difficult, but as usual, practice makes perfect. After about eight or nine tries, I was able to beat it successfully. It was fun, and I would like to give a few pieces of advice to other players (my apologies to LazyMuffin): do your best to master rapid-firing; done properly, you can keep the starting cats off your wall for enough waves to start upgrading. Firing before the cats get on the screen is a good way to take out a few before they become an issue. And finally, annihilate the hairball-spitting cats with extreme prejudice, because when they start really increasing in numbers, they will destroy your wall like it's nothing. Do your best not to get hit, upgrade ASAP, and practice and you'll win soon enough.
Fun game!
Awesome game!
But I find a bug in the game! At the boss, when I try to retry, I die instantaneously and get back to the upgradepanel!! Really annoying when i've come so far :P
Bit to difficult, yet some great style and humor.
I enjoy a challenge, yet this one seems a little unfair. I suppose with enough effort and time you could pause after every shot. Yet even with the hotkeys it feels crushing. Yet the humor and style of the game is so good was that I was pissed of I couldn't get farther in the game to see more of it.
So I would say 7/10, not bad for sure.
Also I want to see more games from you guys.