A cave split in two
Handy Dandy is a 2D puzzle platformer where a mishap sends an inter-dimensional tear through the cave. Handy and Dandy end up on opposite sides of it, and the cave itself gets torn apart along with them. The two adventurers have to progress through the cave, solve what it throws at them, and get back together so their world can be united again. The game runs over 40 levels across 2 dimensions, with 1 barrier sitting between them, and takes a bit over an hour to get through.
Playing it together
This one is built for two people from the ground up. Each player takes one of the adventurers, and the levels are designed so that you have to work as one to get both characters through. Progress depends on coordinating with the other side rather than one person carrying the whole thing, which is where the testing of friendship and patience comes in. Remote Play Together is supported, so you can bring a friend in even if they are not sitting next to you.
Before you start
Expect short, focused levels rather than a long campaign — the whole run is a bit over an hour across more than 40 stages. The split between 2 dimensions is the core of the design, so a level that looks simple on one side may hinge on what is happening on the other. Bring someone you can talk to while playing, since talking through the puzzles is most of the experience. Handy and Dandy would thank you for it, and if they had arms they would give you a hug, but they do not have arms, so they cannot.