Best. Flash. Game. Ever.
If you've played any of Super Mario Bros. Crossover for any length of time, you'll come to the same conclusion that I did: Best. Flash. Game. Ever.
The Flash game is a result of Jay Pavlina's desire to make a game, and for his first effort ever at programming something – it's superlative. And now the amazing take on the classic is about to get upgraded with a ninja.
Super Mario Crossover Ryu Hayabusa
Check out an interview with the game's creator here.

I'm pretty sure he would get smoked by the first enemy. For realz, what can he do without a mushroom? Jump....