About Fireboy and Watergirl
Fireboy and Watergirl 3 sets its puzzle-platforming inside the Ice Temple, and the entire design revolves around one core restriction — Fireboy can walk through fire but dies in water, Watergirl is the exact opposite, and every puzzle in the game is built around that asymmetry. It's one of the two-player picks on classrooms6x.bitbucket.io, and it holds up as one of the better cooperative games on the site if you've got someone to actually play alongside.
Controls
Controls split cleanly down the keyboard for two-player sessions — Fireboy uses the arrow keys, Watergirl uses WASD — which means both characters can be controlled from the same keyboard without any special setup. Each character needs to reach their own colored exit door, and gems are scattered through each level as an optional collectible for players who want more than just a clean finish. There's no timer pushing you through faster than you're comfortable with either, which fits a game built around careful coordination rather than speed.
Puzzles Built for Two
The puzzles themselves are built around forcing genuine coordination rather than letting one player carry the level alone. Switches often need to be held down by one character while the other moves through a newly opened path, platforms sometimes require both characters standing on them simultaneously to trigger, and blocks occasionally need pushing from angles that only make sense if both players are actively paying attention rather than one just following the other around. A level rarely has an obvious solution that one character can solve solo — the temple's mechanics assume two people who are actually communicating, or at least paying close attention to the same puzzle from different angles.
The Green Pools Exception
Then there's the green pools scattered through the ice temple levels, which break the game's usual asymmetry entirely — they're lethal to both characters regardless of the fire-or-water rule that governs everything else. That single exception forces a different kind of caution than the rest of the game demands, since neither character gets to treat those pools as safe just because of their usual elemental immunity. That single design choice is a good example of how the temple's level design occasionally breaks its own rules just enough to keep players from getting too comfortable with a pattern they think they've fully figured out.
Playing Solo
Playing solo is entirely possible too, with control switching between the two characters as needed, though it changes the pacing considerably compared to having a second person handling one character while you focus on the other. Solving a two-character puzzle by yourself means constantly swapping control back and forth, which slows down the rhythm of a level but doesn't block you from finishing it. Once you've made it through the Ice Temple, 6x games offers a wider mix of puzzle and platformer picks worth checking out next.