I have the original ported Doom on my iPhone and the game play needs a bit of work. You have to tilt the phone forward to walk(which ends up running at full speed most of the time) and you turn by hitting 2 arrow buttons at either side of the screen and above the arrows are the buttons to shoot.. There is no way to move back and no method to strafe.. Its not a very intuitive method of playing the game and Ive really only started it up a few times to show other people it exists.. i hope this new version is more fun to play.. but they better have a 'Lite' version for free because Im not paying for the game to find out it blows chucks like the original port.