Get Super Mario Bros. 1 & 3 Mashed Together to work with a NES core?

I recently watched a YouTube video on the channel Blue Television Games where they played a special kind of rom hack for Super Mario Bros 1 on the NES called Super Mario Bros. 1 & 3 Mashed Together.

I’ve run countless rom hacks with RetroArch in later years, but what’s unique about this kind of rom hack is that at its current state this kind of rom hack seems to only run on special NES emulators “on steroids” (fceux and mednafen), thereby not making this rom hack compatible with original hardware.

I know the Mesen NES emulator has got support for custom graphics in recent times, but this rom has the extension *.nesm which I suppose is a new custom format for NES roms.

It looks like those emulators have been modified, but there’s no source for the changes, is there? If not, it’s violating the license of the emulators (both of which are GPL, AFAIK). If the source is available, it could potentially be applied to FCEUmm (depending on what all has been done).

I have now asked on the discord server of this rom hack if there are sources available for the special builds of those emulators, I hope I will get an answer soon.

It seems like there’s only a forum thread and a discord server related to this rom hack. The author of this hack goes by the name Corpse Grinder, so there’s at the moment not much information to go by it seems.

Its apparently using features from VTxx extended famiclones.

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I got a response from a user named you_are_doomed on the discord server for this rom hack, I asked:

“Are there sources available for the special builds of those emulators which are able to run this rom hack? If so, maybe these changes could also be applied to some of the NES emulator cores in RetroArch, enabling more emulators to run this rom hack.”

Then the user you_are_doomed responded:

“this core is exist, but unfinished, I need complete fceux, then I can make all changes for libretro-fceumm”

“modified core on github, but probably world 8 will have incorrect colors”

I created a Feature Request on the libretro-fceumm GitHub page a couple of hours ago also regarding this, so help may be on the way.

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Some news from the user you_are_doomed on this rom hack’s discord server:

“supported modified emulators - fceux, mednafen; testing - retroarch core”, posted two days ago.

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I haven’t tested this core yet, but it seems you would need to use the source files to manually compile the new libretro core that’s needed to play this rom hack.

The user you_are_doomed on the discord server has mentioned that he will compile the dll file for this libretro core soon, thereby making it easier for casual users to enjoy this rom hack without installing msys2 with all its dependencies and such to compile the libretro core dll file (I have msys2 and dependencies installed, so I’m good).

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I just build this core myself and posted it in the Discord server for this rom hack (I have a different username there). The rom hack works just fine with this modified fceumm libretro core in RetroArch, just tested it out in RetroArch.

It seems like I can’t post attachments here, but if you join the Discord server of this rom hack (, then go to en_chat, you will find this compiled libretro core dll-file in the chat history.

It would be cool to have this modified libretro core included in the libretro buildbot, but as far as I know there’s only 1 rom hack utilizing this modified core, thereby the libretro buildbot could end up very crowded if a lot of emulator cores made for 1 rom hack occupied the libretro buildbot.

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