Welcome to the work of pest control from other planets! you just need to kill pests from other planets and be careful not to be devoured by the "Bigger Pests", use a repellent to kill the smaller pests. But if you use the repellent on the bigger pests they will simply run away, just be careful how many times You use the repellent because it might run out, and if that happens, go back to the ship and refill the repellent. Your goal is to kill 99 pests, good luck!