This is probably the best platformer I've ever played. The controls are snappy and responsive, the levels are tightly designed, and the difficulty curve is nearly perfect. Every level is fun on the first playthrough, and still fun on a speedrun or completionist playthrough. The bonus levels explore the game's mechanics in ways you would hardly imagine when first playing the base game, while also creating some of the most satisfying challenges in any game I've played. The story is simple but does a good job conveying its themes, and the simple but well-developed characters are fun to see interact as they progress through their own arcs.