Rayman Gold is a popular 2D platform game that runs in the MSDOS setting and is totally free. It features a fun being whose main weapon is its fists, which it throws at its enemies.
As with all platform games, in Rayman Gold you have to run, jump, climb and avoid enemies, although you also have some friends who give you bonuses or guide you, like fairies, wizards, photographers (to capture a moment and then let you restart from that moment), magic seeds, musicians, etc.
The main aim of Rayman Gold is to run through the 5 magic worlds until you defeat Mr. Dark, and so free the electoons who are being held as prisoners.