You can play as Luigi in Super Mario Galaxy, but it depends on which game you mean and your progress. Here’s the breakdown:
🌌 Super Mario Galaxy (2007, Wii)
Unlocking Luigi:
After you collect all 120 Power Stars as Mario, Luigi becomes playable.
This is essentially 100% completion, so you need to finish every galaxy with Mario first.
What Luigi Changes:
Higher jump than Mario
Slightly slippery movement, making some jumps trickier
Stars collected as Luigi count toward total 120 Stars, allowing for a “second run” and unlocking the Grand Finale Galaxy for true 100% completion
🌌 Super Mario Galaxy 2 (2010, Wii)
Unlocking Luigi:
You don’t need 120 Stars in this game.
After collecting 30 Stars, Luigi will appear at certain galaxies and can take Mario’s place for a level.
Luigi’s Abilities:
Same as in Galaxy 1: higher jumps, slippery movement
Stars collected with Luigi count toward your total progress
✅ Answer in short:
In Galaxy 1, Luigi is playable after collecting all 120 Stars with Mario.
In Galaxy 2, Luigi appears after 30 Stars and can play select galaxies.