Jay Pavlina's not done with his awesome-sauce Super Mario Bros. Crossover. It's totally getting post-release support. And an update on the way June 25 will give Link, Samus, Mega Man et al. even more powers and attacks.
A new options menu shortens Mega Man's jump but gives him Rush Coil to get over taller obstacles, more true to his jumping ability in his games. Samus can crouch and fire; Simon Belmont can change direction in midair with his double-jump; Link can attack up or down and Bill from Contra can - well, Bill from Contra doesn't get anything extra, he's already so badass.
Mario also can swim/fly through any level thanks to a cheat menu (great cameo by Ryu Hayabusa); and Crossover will get five difficulty settings, with character-appropriate sound effects.
Too bad this isn't out in time for E3. It'd get my Best of Show vote for ... something. Read more about it at Exploding Rabbit (Pavlina's studio) or brush up on your Super Mario Crossover skills at Newgrounds.
Update: Commenters Nosfer and PeteyCoco note that Ryu Hayabusa from Ninja Gaiden was previously announced as a playable character for this next update.
[thanks Greg B. and all who tipped this]