You're talking about Play as Mario. That's a mutator, which means it can run in any level, including single player levels, though unfortunately there's not a good built-in interface for making that happen right now. What you can do though is create a dummy level, let's say marioifier.j2l, and then write the following marioifier.j2as script:
Code:
void onLevelBegin() {
jjChat("/mutators mario on");
jjNxt("diam1.j2l", true, true);
}
(but replacing "diam1.j2l" with whatever other level filename you want to play.)
That's not a great solution, but until we make some more code changes it's probably the best you'll get. :# As for other characters from other spritesheets, pretty much the exact same code would be involved, based on my snippet--the hard part is assembling the custom .j2a with the full roster of player sprites.
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