Sonic Battle Classic
The Matrix has 96 adventure games on file for the Game Boy Advance, released between 2001–2007. 17 of them support multiplayer, including 2 with co-op. They're ranked below by legacy score, so the games that shaped the genre on the GBA come first, with lesser-known picks further down.
Adventure games focus on exploration, story and puzzle-solving rather than combat. Progress comes from examining your surroundings, collecting items and figuring out how they fit together.
Typical commitment: weekend project (roughly 6–20 hours). Tip: Classic adventure games can be cryptic by modern standards. Take notes, try everything on everything, and save before risky choices.