Super Mario 63

A fan-made platformer that takes a water-pack traversal system and builds an entire game around it. The hover holds you in the air, the rocket launches you upward, and the spin crosses horizontal distance — and every level is designed around which of those three the situation needs, which gives the movement a puzzle quality most platformers do not have. It is a large game. There is a hub world, dozens of stages, collectibles that gate progress, and a level editor — an amount of content that was remarkable for a free fan project and remains substantial. The level design is genuinely good rather than merely faithful, with stages that introduce a use of a movement and then test it, and a difficulty curve that rises without becoming punishing. It takes hours to complete, saves progress, and plays best with a keyboard. The presentation borrows heavily and the design is its own, which is the correct balance for a project like this. It runs on anything and needs no download. One of the better examples of what fan development produced in the Flash era, preserved and still playable. The level editor deserves a mention of its own: it exposes the same tools the campaign was built with, which means a player who has finished the game has somewhere else to go and a reason to look at the design more closely.