Admittedly I should have picked up that bug in Super Mario Bros myself if I had done a full playthrough. And thanks for reporting the Zelda issue. Someone else did report that as well and both those issues require a rewrite of a large part of the code related to how the movement is implemented which will take some time. Hopefully it doesn't detract too much from playing the game until I find time to rewrite and test the code.
Viewing post in Bug report? Super Mario Bros. level 8
Sorry to report another issue.
Good news is that world 8 is fixed and playable, but the elevator at the end doesn't work. You can jump a couple times to get to the princess and finish the game, but yeah, there's something wrong with the platform.
I've uploaded my playthrough to YouTube. You can see what I'm talking about after the 10 minute mark.