Whatever the reason may be, the action is one of the most thrilling you will find in an alien-themed slot game. No one knows why these extraterrestrial cows are here to invade earth, but it may have something to do with the green pasture � or the plight of their dumber cousins on earth. Its alien-based theme is somewhat bizarre, considering that the invaders are space cows in space ships that look too small for war or comfort. Invaders from the Planet Moolah slot is exceptional, as already highlighted.