@jordanhuckaby

Update if anyone is looking for a solution:

I confirm I now have a working solution to play Backyard Football 2-Player using two built-in joysticks.

Since lr-scummvm already recognized the first joystick as a mouse, I left player 1/joystick 1 untouched. My problem was with joystick 2; ScummVM would not recognize this as a keyboard, and thus Player 2 could not control anything.

I used xboxdrv to configure the second joystick as a keyboard when ScummVM is used. This was done by editing the runcommand-onstart file, as outlined here: https://retropie.org.uk/docs/Universal-Controller-Calibration-%26-Mapping-Using-xboxdrv/. Since Backyard Football only needs the keyboard directional keys and the right-control button, I only mapped these (joystick as the directional keys, and a cabinet button as right-control). Once ScummVM closes, this virtual keyboard gets eliminated through the use of the runcommand-onend file (again, in the doc linked above).

After doing this, a notification would appear when opening ScummVM mentioning that an X-Box Keyboard Emulator has not been configured. This was a positive sign because it shows that the virtual keyboard was being created by opening ScummVM. Unfortunately, Player 2 still was not configured to use this keyboard.

The final step was then editing the retroarch.config file for ScummVM. I first had to map Player 2 to use the new virtual keyboard, which was done by pointing to the new joystick number (2 in my case). I also had to re-do the B=right-control mapping in retroarch that was done in the runcommand-onstart file.

After doing this, Player 2's movements were being registered in ScummVM. Strangely, Player 2's movements were also moving the mouse cursor (Player 1). The final step was to tell the retroarch.config file that player 1 should not have any keyboard functionality. I did this by manually mapping each directional key and right-control to "nul" for player 1, similar to the following: input_player1_up = "nul". Now, moving joystick 1 controls player 1 (mouse), and joystick 2 controls player 2 (keyboard, via xboxdrv).

Good luck!

@mitu Thanks for replying. My gamepads mirror each other, and have the same number of buttons installed and mapped to the same keys. I'm aware that the gamepads won't work correctly if there are any differences at all. In fact, I had to add two extra buttons to the player 2 USB encoder in order to make it mirror the player 1 USB encoder precisely. Initially, we had installed two extra joypad 1 buttons to serve as a hotkey/escape and as a pause button, but they wouldn't work without identical buttons set up in joypad 2. The joypad 2 buttons are actually inside of the cabinet, because there are no holes for them on the control panel. I've already used jstest many times, too. So, I can promise that the two joypads are configured identically, and I haven't set up any player 1 buttons in the 800/5200 emulator that map differently from player 2. I know better.

I really do think the problem is that the Atari 5200 emulator isn't yet set up to recognize multiple fire buttons for player 2. I found a discussion on this forum from May 2016 entitled "Atari 5200: New version of Atari800 (Beta): two triggers (Moon Patrol), hat start and exit buttons" where user jfroco discussed a new port of Atari800 that added trigger1, trigger2, asterisk and hash support for joystick buttons, but only for player 1. A later post from user Veramacor (April 2017) detailing atari800.cfg settings also reflected trigger1 and trigger2 support on Joystick 0, but not Joystick 1. Then, in May 2017 user Used2BeRX asked user future.child if they would be able to properly code the player 2 controller to allow two-player games. It's not clear from the subsequent conversation that this ever got done in the way I'm discussing here.

I'm guessing from this discussion and my experiences this weekend that the Atari800 emulator must still be in that same developmental place, because when I tested the 5200 Moon Patrol ROM (I do own an original cartridge), sure enough, player 1 could use the second trigger (button X on my arcade cabinet config), but not player 2. The X button did nothing for player 2. Again, I'm not having this problem in any of the other emulators I'm using with Retroarch (MAME2003, MAME 2003-Plus, Final Burn Alpha, MAME2010, Stella, CoolCV, or the NES and SNES emulators). On those emulators, all buttons work the same for both gamepads. There are no discrepancies.

However, if someone can verify that they are able to use both fire buttons for both player 1 and player 2 in Atari 5200 Moon Patrol (one to fire, one to jump), RealSports Football, etc., I will be more than happy to try to get it working for Player 2 in Retropie. I just haven't seen anyone confirm that there is trigger1, trigger2, * and # support for Player 2 in the 5200 emulator. The only evidence I've found is that there isn't such support, and I don't want to spend days futilely trying to set up something that isn't actually supported. In fact, a post from three months ago said that the controller upgrades future.child made from 2016-18 aren't part of the current libretro version of atari800. (That thread also suggested that RealSports Football is viewed as a lost cause because of its need for keypad input.) Maybe the best way to ask this question is, does Moon Patrol work properly for player 2 on the 5200? Can you jump and fire?

Nobody talks about soccer anymore. Just found a new game fitting this thread.

Pleasure Goal / Futsal - 5 on 5 Mini Soccer (NGM-219)

Rom name: pgoal.zip
Emulator: lr-fbalpha (FB Alpha v0.2.97.43)