Tendo City

Link.

It is a flash game which is essentially a straight copy of Super Mario Bros.-- except you can now play using other classic NES characters. Each of them control like they do in their own games, and all have special moves unique to them. It's amazingly fun and very well-made.

You can play as:

Mario, from Super Mario Bros.
Link, from The Legend of Zelda
Bill, from Contra
Simon Belmont, from Castlevania 2: Simon's Quest
Samus Aran, from Metroid
and Mega Man, from Mega Man

^Thank you, Ryan. You've introduced me to this when I have to study for a test. Kiss ass.

Cool concept, but the fact that anyone can kill enemies by jumping on them definitely cuts down on the difference between characters...

It kinda has to be that way, though. Most of those characters no longer have life bars.

True, but it does feel a little odd. I also noticed that all characters with weapons seem to kill enemies in about the same amount of hits, and that using weapons takes multiple shots to kill enemies, while you could just jump one them once and kill them. It kind of defeats the purpose of making them feel different... I mean, they are, but they also aren't. They can all also jump as high as Mario too; though that's necessary to get over the obstacles obviously, Link jumping so high looks odd. :)

It is a kind of cool concept, though, and it sort of works.