The X-21 Space Saucer is a replacement model for the copters in the DLC campaign Invasion! They are encountered fequently in all 3 levels and come in great numbers ranging from a measley 10 to a whopping 50. They are one of many whacky model replacements in Invasion! that make the campaign so enjoyable
these flying saucers are completely defenseless but make up for it in large numbers which they swarm around in the sky and then fly direcley into the players Toy box, the saucers are very weak and should only take a level 1 Anti Air to destroy
- An achievment is awarded to you after shooting down 40 UFOs with your P51 Mustang in a single level.
- The box art for the Space Saucer says "will not fall off table" indicating that the real life toy persona of the Saucer is a battery operated wheeled toy either being switch operated, wind up, or pull-back.
- The X-21 is based off real life tin saucer toys, one of which is known as Satelite X-11 which sounds very similar to the X-21 Space Saucer.
- X-21 space saucers are piloted by Cosmonauts