Wait for it to run towards you, stop suddenly so it begins to pass over you, grab on to its weird dangly tenticles and use them to swing up onto it's back and commence riding it like a pony.
Grab it's leg and suplex that motherforgeter into the ground
Try again, but this time smash it into the ground instead of PootisLand
Sell the alien corpse to an Alien Fighting OrganizationReinforce the town like Juncoph said