If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
This is a story of one of the characters from the film Wreck It Ralph, where he has to deal with the difficulties after an experiment which went wrong in a lab. Mutated insects are now free and destroy everything standing in their way. Destroy these dangerous enemies before they cause a catastrophe.
Use your mouse to aim and shoot the Aliens.