What Mosa Lina is
Mosa Lina is a 2D puzzle platformer built around random tool and level selection. The levels and tools are handmade, not procedurally generated, but the game picks them for you at random and sometimes modifies them slightly. That means you can get the same item ten times in a row, or finish a run without ever seeing a particular one. Each playthrough only contains a fraction of the total levels, also chosen at random, so nobody knows what's coming next.
The goal in a level is simple: collect fruits to open the portal. How you get there is the whole game. The player, tiles, items and obstacles all run through the same physics engine, so everything interacts with everything else. The developer has said it's impossible to guarantee that every level is beatable with every combination of tools, which is deliberate. There is no premeditated solution waiting for you, so you have to invent one on the spot.
Playing it with friends
Mosa Lina supports local and online multiplayer, so a friend can sit next to you on the couch or join from far away. The shared physics and random tool draws turn into co-op material fast: two players juggling the same unpredictable kit leads to improvised plays, failed attempts, and ideas neither of you would have tried alone. Since the game keeps handing out problems it has never seen solved, having a second person doubles the number of approaches you can test at once.
Before you start
Expect randomness to be the point rather than a rough edge. You will sometimes get tools that seem useless for the level in front of you, and sometimes get repeats in a row. The game rewards treating that as material to experiment with instead of a setback to grind through. Nobody has a fixed walkthrough to follow, so a failed attempt is just information about what the physics will and won't do.
If you finish the base game and want more, the built-in Level Editor lets you make your own Level Packs, and the Steam Workshop holds community-made packs aimed at players who want an extra challenge.