Freedroid is a Windows and Linux remake of a Commodore 64 game called Paradroid. In this game, you play a droid (the Influence Device) that has to seek and destroy robots on multiple decks by either shooting them or taking control over them by winning a subgame (hold down the space bar while close to one of the robots to enter the subgame). To move to another deck, you have to move onto the an elevator shaft and press the “e” key. The elevators look like this:
If you’re playing under Windows, make sure you download the SDL libraries and place them in the same directory as the Freedroid executable. The classic version, along with the SDL libraries, are just over 7 MB.
There is also another 3D RPG version of the game from the same site if you can’t get enough Paradroid – it’s over 100 MB though! You can find some screenshots of this version from the “Visuals” menu on the Freedroid site.