In-game reset: Press A + B + Start + Select
during game play to reset most Game Boy and Game Boy Color games.
Information in this section was contributed by Chris Enoch
and jmis588215.
Invert colors: Press Right + B at the Game Boy logo
to reverse the screen and sprite colors. This may make the game
easier to see in dim light.
Information in this section was contributed by Mike
and Majora.
Other colors: Other color schemes (as stated in the manual) may be
selected at the Game Boy logo by pressing the following combinations.
Note: This only affects regular and not color Game Boy games.
Information in this section was contributed by kaphilli,
Tom, Nik98bag, carters,
Mark, and others.