This Game Boy Advance game was designed by Hideo Kojima with a special cartridge capable of detecting levels of sunlight and modifying gameplay accordingly. Players take command of Django, a vampire hunter, and begin a quest to save the world from hordes of evil demons. However, Django is a much better hunter during the day, and daylight also makes his prey weaker. The game cartridge senses the level of sunlight -- depending on whether the player is inside or outside, and if it's a sunny day -- and adjusts the difficulty level accordingly. The world of Boktai is full of spiders, vampires, zombies, and other foul creatures, so Django needs all the help he can get. Some of the enemies can be killed with a special "solar gun," but others have to be lured outside, into the sunlight.