Recently I discovered that people have actually started working on Mushroom Kingdom Fusion again, after it was in hiatus for a long time. It used to be maybe my favourite fangame ever, combining all kinds of different franchises while still keeping the Super Mario Bros 3 / Super Mario World style gameplay.
The game still isn't finished but I'm surprised they're working on it at all.
Levels included in this video:
00:00 Intro
00:25 5-6 Lair of the Leviathan (Normal Path)
08:45 5-6 Lair of the Leviathan (Hardcore Path)
20:11 5-7 Fiddler's Green
30:07 Ghost Battle
32:51 5-8 Vortex of the Siren