Its a button that opens a window to a website with the game

ok

it's good but not offline and there is a lot of add popups

good

bom a extensão e boa mas o mario nao pula e o som e ruim melhore! this extension is ok but this sound is bad and mario has no jump

After you know the controls, it seems to work pretty well. It opens a new window outside of firefox on which it runs the game. You can play/pause and quicksave the game, edit the sound, and controls.