Mushroom Kingdom Fusion is a "fan game" that has been in development for a long, long time. I remember playing it on my old netbook years ago when it was buggy and unfinished. As of this year, though, the game has hit version 0.53, finally making it stable enough to play through most of the game without using cheats like debug mode.
But what IS it?It's a platformer with characters, levels and other content from all across the video game 'verse. I'm not actually sure there's a story behind it all, but basically, you can play through levels as many different characters (Mario, Link, Sonic, Roll/Megaman, Simon Belmont, uh, there's a lot) and travel through worlds like the Mushroom Kingdom, Alternate Earth, Mobius and Gehenna. Each character plays differently, but they operate as they would in their original games, for the most part.
What's cool about it?*MKF has a LOT of content. There's more stuff in here than I've ever seen in any crossover fan game. Unfortunately, a fair bit of the later worlds are unfinished. Some levels are still a bit buggy, but these have been blocked off and are only accessible in debug mode.
*Variable challenge depending on the character. I prefer to play as classic Mega Man just because of the difficulty - he can't jump as far as other characters, so you have to get good with his "slide jump."
*Collectibles. In addition to your normal coins and power-ups, you can find rupees (used to pay for stuff in shops) and cherries (which summon invincibility stars when you get enough). Some levels also have red coins that are a challenge to find but reward you if you collect 'em all.
*Lots of secret paths. Took me a while to figure it out, but any time there's a locked door next to a level on the world map, that means there's a secret, more challenging path through said level to unlock it. Often the secret paths are related to what they unlock, like the Subcon path ending in a battle with Mouser.
What's less cool about it?*A couple major characters are still unfinished. I wanna play as Kirby
*It's a game maker game, and game maker does not manage this game's resources well. The system requirements for CPU and memory are large compared to other 2d fan games, but I've managed to run it at full speed on my old 3ghz dual core laptop.
*The difficulty can be a bit crazy sometimes. I'm looking at you, Bridge Zone Eggman.
So basically, if anyone's interested, download the huge game and its music and get to playing! I look forward to hearing others' impressions.