So you have 5 spare Roomba autonomous robotic vacuum cleaners and nothing to do with them. Here’s one for you. Dress up four of them as Ghosts and one as Pac-man, re-program them and play the real life Pac-man game.
This is exactly the idea that 5 clever guys from http://pacman.elstonj.com/ had to showcase the extensive Unmanned Aerial System software suite that they have developed to support a personal research.
They laid down some red tape on the floor and dressed up 5 Roombas like Pac-Man and ghosts. While the Pac-Man bot is controlled by a player, the ghosts all run autonomously, giving chase once they’ve spotted him. The original vacuum functionality also comes handy when the Pac-man is supposed to eat white paper dots in the maze.