Boktai: The Sun Is in Your Hand

Following in his father's footsteps, you play Django the vampire hunter, who uses the power of the sun to defeat the many evil beings that infest the world. Search out the various levels for the evil inside, and destroy the immortal that rules the area to complete the level.

Hideo Kojima, the man that's most known for bringing the Metal Gear Solid series to life, has come up with an extremely ambitious idea for the Game Boy Advance: harness the energy of sunlight for a videogame. Enter Boktai, a vampire-hunting action and adventure game that not only encourages players to get outside and play in the fresh air...it almost requires it. Utilizing a special cartridge with a built-in a sun sensor, the amount of sunlight outside the game determines how much sunlight shows up in the actual adventure. And since the player's gun is actually fueled by sunlight, the more sunlight you can get the stronger and more capable you are in the game.