Miracle Ropit's Adventure in 2100 is an action platformer featuring the titular robot, piloted by a young girl. When the robot is hit, it will break down and dump the girl out. The girl cannot shoot enemies, and will die after 30 seconds if she cannot restore the robot, which requires special items. The game often requires shooting at or jumping on certain unmarked spots repeatedly, either to uncover secrets or even to make progress in a stage at all. In order to reach the true ending, two loops of the game must be beaten.

One day in the year 2100, a UFO from an alien planet suddenly appeared and attacked the Earth. A young brother and sister were hiding from the UFO, but somehow have warped into another dimension together with the UFO. There the girl meets a robot who was tracking the UFO. Together with the robot, the girl must reach the UFO's base to rescue her brother and return back home.