Game Background:
You and your fellow Alien Lieutenants have fallen out of favor with the Supreme Leader, Qlepptar, after your terrible performance on the last plundering mission in the Andromeda Galaxy. Now the opportunity for redemption has arrived with the announcement of the next target – Earth!

Your alien race – The Frantrexxians – exist for one purpose… to travel the cosmos in search of precious metals that can be pillaged from planet after planet. The method is simple: knock off the species on the top of the planet’s food chain by implanting destructive weapons inside a lesser species. In the case of earth, that would be humans and cows, respectively. Once the greatest local species is eradicated, alien crews can easily swoop in and take all the planet’s mineral treasures.

For decades, scouting missions have come to earth to capture and probe these unfortunate bovines. Armed with the basic knowledge of these four-legged creatures, you must now work with the Frantrexxian scientists to find the most efficient and powerful ways to turn these animals into weapons of mass destruction! The most successful player will become Qlepptar’s new First Officer!

Object of the Game: Destroy the most earthlings by capturing and weaponizing cows, and releasing them back to Earth to inflict mass destruction!

Game Play:
Once Earth and The Mothership are set up in the middle of the playing area, players are dealt 7 action cards. They then take turns drawing 1 card and taking 1 of 5 actions:

Research a Cow Weapon.
Discard 1 Card or Swap 3 for 2.
Recruit or Steal an Alien Scientist.
Operate the Tractor Beam.
Steal a Cow Weapon Research Card.

Players will research cow weapon types, then use the tractor beam to capture and weaponize cows, and release them back to Earth to inflict damage. Damage is determined by both the amount of research cards in their weapon stacks, the rolling of damage dice, and skill points for Alien Scientists in the players possession.
When all the Earthlings are wiped out (or no more cows are left in play), the game is over. Players count the number of Earthling Meeples they collected plus the +2 Extinction Bonus token (earned by the player who wiped out the last Earthing), and the player with the greatest total wins - and gets promoted to Qlepptar's First Officer!

—description from the publisher

Demo Derby Smash-Down!