Awesome free game named Super Mario Crossover 3
Here is the link to play Super Mario Crossover 3.
The game is made on the Super Mario Bros 2 map and the modifications that were made are basicly the ability to choose a lot of different characters. For instance you can run trough the Super Mario Bros map while playing a Link, Mega Man, Samus and many many other characters.
Here is the link to play Super Mario Crossover 3.