Boktai - The GBA series that has Kojima's fingerprints all over it.
A set of twin brothers, split by conflict, one serving the sun, the other serving the darkened Immortals (for his own reasons).
Stealth action (sneaking, sound-luring mechanics)
...and a solar sensor on the board, created to absorb sunlight to charge your weapon - The "Gun de Sol" - as well as to charge the "Pile Driver" system, the only method capable of destroying an Immortal, typically making up the secondary half of each boss fight (Phase 1, boss fight proper, each with their own unique mechanics. Phase 2, dragging the coffin they leave behind from the boss chamber to the Pile Driver outside, leading to an Immortal Purifcation sequence - You charge the Piledrivers while the immortal fights back with one mechanic.
...So long as the sun's out. The Piledrivers will *not* function without sunlight hitting the sensor.
Imagine Kojima just taking your gameboy advance away and telling you to go the fuck to sleep.
