How to develop games on Nintedo Vs. Dual System

I have not heard nor seen anyone talking developing new games for Nintendo VS. Dual System.
In the nut shell, VS. system share many games with NES/Famicom library such Super Mario Bros, Duck Hunt, Excite Bike, etc... but slightly different in many ways.
I'm just curious if there is a way to convert Famicom/NES to Nintendo VS. system?

Porting an NES game to Vs. Unisystem involves palette remapping, swapping the controllers (Vs. plugs player 1's joystick into controller 2), removing reliance on nametable mirroring (Vs. uses all 4-screen all the time), and rebalancing it for the shorter sessions of coin-operated play. Vs. Dualsystem is two Vs. units communicating through a shared memory chip.

As for the time and effort involved in making an NES game use this shared memory: I imagine there aren't enough Vs. Dualsystem units in circulation to make it an interesting platform.

I see. Seems to be so complicated. No wonder there is no NES romhack conversion for VS. Unisys
But on other hand, i think it's very niche and yet very interesting system that not many people mentioned much.

Vs. Dualsystem is an interesting machine concept, which was very underused. There's a whole thing about the two players being presented with asymmetrical information there. Maybe Tennis came closest to exploiting this with its mismatched viewpoint. Ultimately even Nintendo wasn't interested enough in this machine to make truly new games for it.

You can emulate it in Mame, I think, and probably some other emulators, but the side by side view isn't ideal. The Wii U pad would have been a good system to emulate it on, maybe? Netplay might be good, at least if the lag isn't a critical problem.

It's not a very common machine, and it takes up a lot of space with the back-to-back arrangement.

So... the big question is where and how are you going to play this? ...and also what kind of idea do you have that would make it worthwhile?

There's some information on the Wiki but it's a little disorganized:

http://wiki.nesdev.com/w/index.php/Vs._System
http://wiki.nesdev.com/w/index.php/INES_Mapper_099

I'm kind of the opposite opinion from Tepples here.

Simpler games often just work despite being given 4 screens of nametables. The existing hardware is approximately equivalent to mapper 87 or CNROM, but both can be easily modified to compatibility with the Vs. System's mapper 99. Existing daughtercards allow some MMC1, UNROM, and a few other mappers to work. The Vs. System's 2C03 PPU is similar to the colors in the NES's Famicom.

The big gotcha is something needs to keep the secondary CPU's watchdog timer from expiring. Lupin3rd started a thread asking about this.

BTW, I found this:
https://github.com/cyberkni/NESToVSRoms/

Apparently converts NES ROMs to Mame playable format. Has a list of games it works with.

The converted games aren't going to use the dual thing, but I guess it'll get them running as a start maybe.

I dislike using MAME, the latest versions of Mesen and Nintendulator-NRS support Vs. Dual System pretty well. Now if only they supported PlayChoice-10 as well

I guess my memory is a bit biased, coming off the fact that the last two NES projects I've worked on are something using 8-way scrolling and nocash's Magic Floor. The latter works in 1-screen or vertical mirroring but not horizontal mirroring or 4-screen because it scrolls to the opposite nametable.

It would have been awesome if new game such as Micro Mages can be ported over to VS. as I can see this arcade system is built for 4 players experiences.

miau you guys would like to give VS. system a crack? It would be the first game ever released after 33 years for VS. Unisys