Touhou Kaikeidou ~ Marine Benefit is a Touhou Project fan game made by Primary-Color Space. It has an oceanic atmosphere reflecting some false predictions that Ten Desires would have an underwater theme. Marine Benefit features three playable characters to choose from, each of which has three shot types to choose from. The game features 'Oxygen' and 'Hydrogen' items which, when enough are collected, grant extra lives and bombs respectively. Hydrogen items are also important in that the marker which indicates how many you have also acts as the game's point of collection. Grazing is also important as it increases Oxygen.