Help with 4 player vs series in a cabinet


Does anyone remember before GGPO, people used to play fighting games on Kaillera?

The vs series had a 4 player version. I’m trying to simulate this experience on a cabinet with 4 arcade stick panels. (rather than havinng one person swap in and out the same controller whenever there is a tag). I also don’t want any “fighting” over control of a character like old retro game menus where both player 1 and 2 could control the menu at the same time.

As a start, I thought, put a switch to switch controls whenever a player hits tag, but that wouldn’t work because sometimes (like during hit stun) the tag command won’t actually switch characters.

Then I thought, back in the day, 4 player vs games were actually a seperate entry on the list. but I don’t recall ever downloading a separate rom.
Was 4 player handled by kaillera? or was it a custom rom? Does anybody know the technicalities behind it? Is there a custom rom that allows this to be done offline?

I imagine most of the work for hacking the rom to do this is already done.

Originally I wanted to do this using original hardware, and being creative but I’m thinking that may not be possible due to do this without having access to game memory.

I’m also thinking about setting up a kaillera server on LAN. but I dont want to require the cabinet to be connected to my network.

anyone else have any ideas or solutions? lets brainstorm


IIRC, it was something that Kaillera did.

For an actual arcade board, you’d need something to read the control inputs and switch players whenever it reads a tag command.


Like I mentioned originally on the first post, that was my first thought, but what about when the command is inputted but not at a valid time? For example , during hitstun or block stun How would I make sure that won’t switch players without switching characters?

Reading the tag command is simple enough, you don’t even need a full fledged chip, just something similar to a logic gate. Probably can be done with a few resistors and/ or diodes. connected to just the hp/hk buttons and a switch. the issue is tags during times where the game doesn’t allow tags.

Since kaillera is software and probably doing some netcode which has access to memory, it could probably check and read values to know which character is active. IIRC Kaillera wouldn’t switch player control when the tag command was input during a time which it wouldn’t activate. Maybe I’m just remembering wrong.

Or maybe i’m just not creative enough to somehow cover the instances with only hardware, timing, and button inputs. Maybe I could ask the guys in the ST hacking thread and see if i can get some tips on finding memory addresses and other hacky tips.


Why would you want to use delay based netcode like Kaillera?


Even with the delay the 4 player swap out games were a hell of a lot of fun.


It’s not that I want to use delay based netcode but…


  1. how much lag could there possibly be on LAN?
  2. 4 player support is already built in on kaillera, I don’t have to do any rom hacking or anything.

but again. I would prefer not to need my cab to be connected to the network.


seems like a cool idea, but besides switching when a tag command is triggered is the only thing i can think of that does not involve rom hacking. but as you said, you can press tag at certain situations without actually tagging. I’ll try doing some research on this.


Dreamcast MvC1. Done :slight_smile:


Dreamcast mvc1 doesn’t do 4-player correctly. I think it messes with the meter to make Duo Team work longer or give you more chances to activate it? Can’t remember as it’s been so long since I played that version but I know it’s not the same as the CPS2 version in that respect.

So the 4-player Kaillera version wasn’t a rom hack? Is that known for sure? Never played it but I thought it was its own entry in the emulator rom list.


The Dreamcast MVC1 4 Player easier to set up than trying it with a CPS2 board.

I don’t know how it works with MVC 1 on the CPS2.

Only 4 player games I know of on the CPS2 are Aliens vs Predator and the D&D beat-em-ups 1 and 2
AVP is a 3 button game and players 3 and 4 comes off the kick harness, the D&D games are 4 buttons with the 4th buttons for player 1 and 4 coming from the jamma harness (like many MVS boards) and players 3 and 4 on the kick harness.

You have to do some rewiring if you want to get the 3rd and 4th player out of a normal cab, test rig or super gun.

Perhaps the MVC 1 4-player board is a dedicated Jamma board?


Pretty sure it was just a romhack for Kaillera.


That is good because I can’t find anything of MVC on the CPS2 being a 4 player game


So is this download available outside of kaillera? Is it possible to load up the rom without being connected to a kaillera server?

Is it possible to extract the rom somehow? because again, I don’t remember downloading an exclusive rom for kaillera 4 player. and the romsets I had just seem like standard romets

I never realized dreamcast MvC1 had 4 player. I should check this out. and the dreamcast is definitely easy enough to hack into a cabinet setup