The Bungie-supported, fanmade iPad port for Marathon hit the App Store this morning, and you can grab it now for free -- well, at least in its "standard texture" form. There's a $3.99 high-resolution texture pack available, as well as a $0.99 "Master Chief" cheat mode (options for weapon unlocks, invincibility, etc.).

Before you buy all that, though, you might want to try out the controls first, as Daniel Blezek, who ported the 16-year-old first-person shooter, had to adjust them quite a bit for the iPad's touchscreen:

"There is a left thumb virtual joystick for moving, the 'action' button is tucked under. On the right thumb, you have primary and secondary fire buttons; the weapon switch buttons are at the bottom. There are a few hidden buttons as well.

Touching the HUD motion sensor brings up the auto map. The left and right sides of the ammo display switch weapons and the center toggles between the ammo and inventory displays. The original Marathon didn't have an aiming reticule, and by default the iOS version sticks to that, but it can be enabled in the options.

There is also an option to tap-to-shoot, but two finger tap for secondary fire didn't make it into the final build. Sorry to the lefties out there, a future release will have adjustable controls!"

You can download the Marathon port from the App Store here.