This is one of those games, like YOU HAVE TO BURN THE ROPE or Pick up the Phone Booth and Die, where the title could double as the walkthrough. Killing everything does entail a few very minor puzzles, but essentially you just do what it says on the box. Thoroughness is rewarded.
So it's not very ambitious. Is it fun? Yeah, more or less, but I found that the implementation wasn't quite smooth enough and I actually got hung up on stupid things midway through the game. You have to kill things in a specific order, and if you try to deviate from this order, the game won't let you go forward; since I had completely the wrong idea about how to solve one of the puzzles, this left me stuck for longer than the game really deserved.
Then, too, the humor wasn't quite to my taste. It's supposed to be broad, I realize, but the one-note joke had worn out well before the game ended.