Doom is a 1993 first-person shooter game developed by id Software. Players assume the role of a space marine, popularly known as Doomguy, fighting their way through hordes of invading demons from Hell. 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.