Huh, not a bad game, I like it. It's a cool idea to put all different kinds of retro characters in the Mushroom Kingdom to face Bowser and it plays well too. I'm not sure who is my favorite character since each one is so different but I like playing as all of them. I think that the best addition to the game is having all of the different themes from each of the character's series, which is kind of the reason why I like playing as Megaman in the water levels and Simon in the underground levels. Nice choice for this weeks Alt+Escape John Funk, it's a fun game.
Anyway this game kind of reminds me of two other crossover games that I have played in the past. They are called Megaman vs Metroid and Megaman vs Ghosts 'n Goblins and are essentially mashups where you play as Megaman and have to traverse through Samus or Arthur's level while killin enemies along they way. At the end of each game, you face either Samus or Arthur which is challenging but fun. If you beat them you collect their power which can be used in that stage or even be transfered over to the other game. They are both really fun games and they have some cool extra features for some replayabilty. Both of the games are here if anyone wants to play them.
http://www.brokenfunction.com/