Pokémon FireRed Version and Pokémon LeafGreen Version are 2004 remakes of the 1996 Game Boy role-playing video games Pokémon Red and Blue. You can save your data to your browser. Click the settings icon and press "Save State Location", then change it to "Keep in Browser". You can enter fullscreen by hovering over the game and pressing the fullscreen button in the bottom right If pressing enter causes the game to tab in and out, just click on the middle of the game to refocus.