I’ve tested it (Beta 2) on real hardware, specifically a PAL Mega Drive model MD 1601-18 with a stick mod, playing at 60 Hz on a Chinese Everdrive. I was able to finish it thanks to the invincibility mode. It’s true that there was some slowdown at times, but it’s also true that I stopped killing enemies once I saw I could advance without issues—obviously the slowdowns went away when I did kill them. I did find a few small bugs, which I’ll list below:
• At the end of the bonus stages in demo mode, a bunch of red tiles load before the ninja appears in front of you. During the game I wasn’t able to beat any bonus stages, so I don’t know if anything breaks if you get all the hits right. This red tiles bug doesn’t happen in the actual bonus stage, though it does seem to take a little while to load the ninja in front of you.
• On the screens where Spiderman appears, the top-right tiles sometimes don’t load for one or two seconds. This is noticeable if, for whatever reason, you advance a bit faster than normal.
• The helicopter was indeed a little slow, though not to the point of being a problem, but there were some graphical glitches where numbers loaded instead of tiles.
• At the end of stages 2-1 and 3-1 (I think it was those two specifically), after rescuing the last kid, there was a muffled noise along with the music. It didn’t last long because you only had to go through the door to change stages, and the noise disappeared when the new stage started.
I think that’s everything. I’m really happy with your port and with the idea of the options menu before starting. Seriously, thank you so much, and keep improving it—there’s very little left to match or even surpass the arcade experience. Thanks, keep it up, and best regards.