Boktai: The Sun is in Your Hand

Game Description: Playing Boktai requires sunlight. The solar sensor responds to the player's environment and reflects the amount of solar energy (sunlight) in the game at real time. When there is strong sunlight, solar energy charges up quickly. When weak, it charges up slowly. Sunlight is required mainly to charge energy to the solar gun which is the player's only weapon, and to fight the boss at the Pile Driver. And during moments other than these, the sensor will detect solar energy, causing the game content to change. In Boktai, with the real time clock inside the cartridge, game contents change over time from daytime to nighttime, just like actual time in our world. The Undead that are active during the night stay quiet in the dungeon during the day.