You probably already knew, Boktai uses a solar-sensor. This keeps this game from being ever playable, but it is great!

User Rating: 9.2 | Boktai: The Sun Is in Your Hand GBA
Boktai is a one of a kind game. Using the sun to provide ammo for your weapon, the Gun del Sol, is something only Hideo Kojima could think of. This game resembles a lot with some of his other great games, the Metal Gear Solid series. The main character in Boktai, Django the Solarboy, sneaks through dungeons and caves, knocking on walls to distract enemies and burning them with sunlight. I really liked this gameplay, so I wanted the game to take as long as possible. I waited on every corner, see if I could trap an enemy or steal around it. Sometimes there were some puzzles to solve, but on all three difficulties (one gained after completing the game) those weren't too hard. Still fun though, moving blocks to create your way. It contributed to the RPG-aspect, but Boktai isn't an RPG. I like the title adventure because that's mainly what it is. Your Gun del Sol exists from four different parts. Of all are many versions to be found: the Battery (x1, x2 etc) the Lens (Sun, Flame, etc) the Grenade (Flash, Scan, etc) and the most important part, the Frame (Single shot, Spread fire, etc). You collect the different parts all through the game, in treasure chest that can hold many more items such as a See-all nut, Solar leaf, Red apple etc. This can all be found in your Inventory, together with a map, that isn't always clear. Sometimes it's hard to see where you are exactly. Finally, there also is a multiplayer mode, but I prefer walking through the world of Istrakan alone and unveil the dark plot. As I said, I love to play this game, the entire atmosphere of the game pleased me. The only disadvantage is that the game requires sunlight for optimal fun, although you can save some in the sun-banks.