Fullmoon is a Half-Life 2 modification built on the Source engine.

The game is set in the present day in the Scottish highlands. A group of British Army soldiers have been sent into a remote part of the mountains to hunt down and kill what has been reported to be a giant dog. The creature is causing civilian casualty's in the glens and local villagers are terrified to go outside at night. The soldiers arrive at their destination just before sundown on the evening of the new years first full moon. As night approaches the soldiers are radioed by their commander that they must meet with a man living in the forests as he holds some vital information on the beast they are about to encounter.