PtoPOnline, a YouTube channel that specializes in finding unreleased footage of canceled games, has published a video of Grin’s pitch video to publishers during 2004. The game is called The Unknown, a first person shooter set in a submarine. It had an arcade element, with the more enemies killed the higher your combo bonus.
Crew Quarters was the first level and most complete, and some smaller additional levels were also shown off. The player mostly used an assault rifle and shotgun to fight off alien enemies invading the players submarine. Reactor Transit is the final playable level and features a large boss fight against a mushroom/spider hybrid.
Grin previously worked on a canceled Xbox game named Vultures in 2003. The Unknown was their follow up project, though at this time PtoPOnline has no further information on the prototype.