Shadow Jack is an in-development Keen 1 mod by Ceilick. It stars the titular character and its setting is not related to the Keen series. Shadow Jack reawakens in the realm of darkness after previously being killed by his nemesis, the Crimson Void. In the game, the protagonist gains limited special abilities by collecting certain orbs, not unlike the gravity changers in Fall Up. They enable him to shoot, jump higher, fly or to become immortal. There are also energy orbs that allow Shadow Jack to pass through energy barriers if he has collected enough of them.
An alpha demo version with five levels was released on Keen Day 2014. They introduce the functions of the orbs and contain no enemies. The final mod is intended to allow the player to return to levels and play differently based on accomplishments in other levels.