Wario Land 3 Classic
The Matrix has 25 action-adventure games on file for the Game Boy Color, released between 1998–2002. 4 of them support multiplayer. They're ranked below by legacy score, so the games that shaped the genre on the GBC come first, with lesser-known picks further down.
Action-adventures blend real-time combat with exploration, puzzles and item collection. You open up a larger world gradually as new tools let you reach places you couldn't before.
Typical commitment: weekend project (roughly 6–20 hours). Tip: Keep a mental (or paper) map of locked doors and unreachable ledges; most action-adventures expect you to come back once you find the right item.