I think the developer sums it up quite well:
"A friendly gardener game that is all about buying weapon upgrades and killing cute animals. Destroy cuddly creatures with 21 different weapons, but make sure your very stylish hat and nice moustache don't get dirty."
Controls are easy: A and D to move, W to jump, mouse to move crosshair and shoot. I recommend playing with the Gore set to High for the full ridiculous and very bloody effect. Also, leave the "music" on to maximise the insanity.
Friendly Fire [Arcade Bomb]