This game is using Flash! After the 31st of July 2019, your internet browser might start blocking Flash, especially if you use Google Chrome. This means you'll have to activate it to play this game.
Super Mario Bros. Crossover is a fan game that recreates the original Super Mario Bros. and allows you to play it as characters from other classic games. The dream game of the original Super Mario Bros come to life! This has been a thing for awhile now but got around to it. Check out the resources section for more info about the game.