Robot Unicorn Attack is a side-scrolling platform game where the player controls a robotic unicorn and aims to prolong gameplay without falling off the stage, crashing into the edges of platforms, or colliding into crystal stars without dashing into them. The game has had several sequels, including Robot Unicorn Attack 2 and Robot Unicorn Attack Forever.

As for the availability of the game, Robot Unicorn Attack 3 has been removed from the App Store, but it can still be downloaded if it was previously purchased. Robot Unicorn Attack 2 has also been removed from the Play Store, but it can still be downloaded from other sources such as Uptodown. There is a petition to bring back Robot Unicorn Attack 2, which has been seemingly dropped by Adult Swim games and is no longer being updated.

In summary, Robot Unicorn Attack 3 has been removed from the App Store, but Robot Unicorn Attack 2 can still be downloaded from other sources. There is a petition to bring back Robot Unicorn Attack 2, which has been seemingly dropped by Adult Swim games and is no longer being updated.