Kill 15 aliens with the monster truck

The monster truck is first drivable in "The Mighty Foot", but there won't be any aliens to drive over... yet. However, in "The Mighty Foot: Part 2" there will be loads of aliens for you to crush. Run over every alien you see and the trophy/achievement should unlock before you run out of gas. If you happened to miss some aliens there's no need to worry. There will be plenty of aliens in the next Chapter, "Ghost Town", waiting to get killed by the mighty Duke Truck.