Super Mario Bros Crossover is a fan/home-brew flash game created by Jay Pavlina and Zach Robinson.
This game is basically a remake of Super Mario Bros on the 8bit NES, but what the creators of this amazing game have done is a loads of other characters from other games that you are probably familiar with.
Each character has their own skills based on who they are, for example Mario plays pretty much how you would expect him to and Link can use his sword or his boomerang.
Not to give to much away but here are a few of the characters you can play as
this game plays superb as you play and adapt to each character in this super mario world, it really adds loads of gameplay by playing through the same levels with different Nintendo favourites.
In addition to all the playabele characters it also comes with more features, such as cheats, difficulty levels, new modes of play.
check out the trailer
And why wait? just play the game over at http://www.explodingrabbit.com/games/super-mario-bros-crossover
You can play the game here.