Commander Keen +

Commander Keen is a side-scrolling platform video game developed by David A. Palmer Productions and published by Activision in June 2001 for the Game Boy Color. Part of the Commander Keen series, it was released ten years after the first seven episodes in 1990–91. The game follows the titular Commander Keen, an eight-year-old child genius, as he journeys through three alien worlds to collect three plasma crystals to prevent the weapon they power, built by several enemies from previous games, from destroying the universe. The game features Keen running, jumping, and shooting through various levels while opposed by aliens, robots, and other hazards.