Garry's Mod and Physics
One of my favorite games to play is Garry's Mod, Garry's Mod is a sandbox open world game. You can play a multitude of different game types to enjoy. One of the most interesting aspects of Garry's Mod is the physics engine, you can connect a variety of parts together to create massive contraptions from robots, to spaceships. The game is not realistic, though it doesn't really matter in this case, because the game is so fun on its own. The game allows you to do anything you want using a semi realistic physics engine.