I found this flash game a little while ago. The game itself is pretty much identical to the original Super Mario Bros. The difference it that there are 7 new characters added to the game. Three of the characters are Samus, Link, and Mega Man. All seven new characters have their own special abilities based on the games they are from. Ex. Link has his sword and boomerang.
There are Cheats that can be unlocked as you complete various challenges. The latest version of the game also has 5 Difficultys and various modes. The difficulty influences the speed of the time limit clock and the enemies you fight. Survival Mode gives a predetermined number of 1-Ups that you can use to bring various characters to life and/or power them up to Fire Flower level. Any 1-Ups you earn can be used for powering up characters after defeating a boss.
It can be played on ExplodingRabbit.com. Here is the link directly to the game:
Oh yeah, I played this game after watching my brother play it. Where to begin? You get to play as Simon Belmont, Ryu, Megaman and Billy B. In this game! That is epic. And music from those games are inserted into the levels, and they are quiet accurate as well. In world 2-2, if you play as megaman, Bubblemans theme in on. The power ups are great as well, megamans "fire balls" is atomic fire from the 2nd game. I won't give away too much, but it's worth a look. Thank you for posting this game here.