Released in 2003 on the Game Boy Advance, the game told the story of a vampire hunter. Instead of traditional stakes, the hero wielded the Gun Del Sol — a weapon that fired concentrated sunlight. The main feature was a cartridge equipped with a light sensor that charged the weapon only when played in sunlight. More than 20 years later, Kojima revealed how the idea to implement such a sensor came about.
According to the developer, ultraviolet sensors were expensive at the time. However, Konami happened to have unused UV sensors left over from a failed children's toy bear. Thanks to this, Kojima was able to negotiate a better price, and the sensors ended up in GBA cartridges instead of toys.
Kojima also spoke about even bolder ideas: for instance, he thought about adding a breath sensor to the game. Since vampires are afraid of garlic, the player could have eaten certain foods to affect the enemies. But the team did not support the concept.
Boktai is not Kojima's most famous project, but it demonstrates his unique approach.
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Cover author: Kojima Productions. Cover source: Comicbook