Pocket Monsters Go! Go!

Pocket Monsters Go! Go! is a hack of The Smurfs 3 released in the late 1990s for the Game Boy Color. The Smurfs 3 was originally in monochrome, but was colorized in this hack.

Almost all of the graphics from the original game are replaced, and so are the intro and ending text. The intro text is replaced by Meowth singing a poorly translated version of My Heart Will Go On by Céline Dion. Aside from the title screen, the game's use of color is limited, which gives it the appearance of a Super Game Boy game. The game suffers from extreme slowdown, running consistently at about half speed, possibly due to the colorization process.

Source: TheGamesDB