Steam, Tracks, Trouble & Riddles (S.T.T.&R.) is a single player adventure mod, based on source engine (Orange Box) by Valve. It combines two types of game play: an adventure game with complex, 3D-interactive riddles in a fantastic environment and a simulator for track based vehicles.
A short example how EasyRider's Voice will appear in the mod. Ross' original voice was changed by lowering down the pitch by 19%. All background sounds appearing in the game were removed from this demo.