Attack of the Mutant Penguins

Developed by Sunrise Games and released for the Atari Jaguar in 1995, Attack of the Mutant Penguins is one of the strangest video games on any system. (There was also a PC version simply titled Mutant Penguins.)

The game's premise is that evil green aliens from the distant galaxy of "Bleurgggh" have decide to invade the Earth having disguised themselves as penguins, since watching wildlife documentaries left them with the impression that penguins were obviously the dominant species on Earth. Two Earth boys named Bernard and Rodney have to save the world from the alien penguins, by obtaining and wielding various weapons and building penguin-killing machines.

Interestingly, Mutant Penguins constitutes one of the first entries in the Tower Defense genre, long before the concept was popularized by Starcraft and War Craft maps.

Tropes:

 * Batter Up: Rodney wields a mean baseball bat.
 * Bonus Stage: After completing a level, you get to play one of three randomly chosen penguin-shooting games.
 * Doomsday Device: The Doomscale, a giant scale for balancing penguins on.
 * Everything's Better With Penguins: The game has both good penguins and evil alien penguins.
 * Frying Pan of Doom: Bernard's main weapon.
 * Inexplicable Treasure Chest: Treasure chests can be opened by dropping gremlins on them.
 * Live Item: Gremlins.
 * Spelling Bonus: Collecting letters from treasure chests to spell B-A-T or P-A-N will get Bernard or Rodney their main weapon.