This is amazing! I've had the desire to try to modify the VS port for a while, but unfortunately, I haven't had the free time to commit to anything. Thank you very much for your efforts with this project!
There is another game that could also be ported for the NES: Wrecking Crew. But strangely enough, the console version is much better, and this is the reason to not make such a port.
The arcade version is single-screen, unlike the console version - two game's screens plus a camera.
There is this hack on the site:"VS Wrecking Crew" by Morgan Johansson, released March 17, 2021
This ROM-hack makes “VS Wrecking Crew” playable in one-player mode on your NES.
Mapper is converted to MMC1, palette is patched and coinslot-emulation is included.
Not sure if the changes in this hack are exactly what you would have had in mind and account for everything that you would have wanted to change, that is, if you did ever decide that a port would have been worth making, but I've always felt the VS versions certainly deserve more attention than they seem to receive, though that's not to say that they haven't received any entirely, and I'm probably thinking back to more than a decade ago when I was initially interested in them.
But remembering Climber, I thought it would be nice to enable two-player mode for Balloon fighters. The first player controls the camera, and the second one helps to defeat enemies.
Playing together, the players themselves took care not to be off the edges of the screen.
We know this style thanks to games like Contra. Easy mode can allow players not to burst each other's balloons.
It would be amazing if a 2-player mode could be implemented, but it's understandable that a simple application may not be entirely practical or straightforward given the technical limitations and whatnot, and/or not come without any drawbacks and shortcomings.
I'm not sure how it could work out due to the available space on the screen, but if you've ever heard of and/or played the NES version of Nintendo World Cup
, playable with up to 4 players, there is a section of the screen dedicated to a mini-map display, and if players are off-screen, they can still tell where they are. Understandable as well, it might still not be such a practical or straightforward solution, as there are enemies that would be off-screen, any interactions with ground, objects, enemies, and other players might not be so easily handled and accounted for, and there really just doesn't seem to be any good part of the screen to commit a miniature map for location tracking.
In theory, with some crazy, super technical status bar IRQ implementation (mapper dependent for compatibility), a map could maybe be added, but it probably still wouldn't be practical or pretty, as everything would probably be squished together and unsightly. I don't know. Just typing on autopilot, I guess. My apologies.
I look forward to any additional ideas and potential future updates you come up with for this hack, as well as any other projects you create that we have the honour of receiving and being able to enjoy.
I wish that there was some way that I could contribute something given that I was intending to try to look at this port, and how much I enjoy Balloon Fight overall, but again, I'm afraid that I just wouldn't be able to promise anything, unfortunately.
However, for what it's worth, if anything, I was really, really excited about this when it was first posted. I was following the original progress for the early attempts for the VS-to-NES conversion that started years ago over at NesDev, and to see the progress now, it is truly a blessing. So, again, thank you very much.