So I actually was able to get single player working but not second player by ollowing instructions here:
https://github.com/RetroPie/RetroPie-Setup/wiki/Neo-Geo
I edited the folioing file:
/opt/retropie/configs/fba/fab2x.cfg
Note: Using /usr/include/SDL/SDL_keysym.h for key mapping
[Keyboard]
# Get codes from /usr/include/SDL/SDL_keysym.h
A_1=306 #lctrl
B_1=32 #space
X_1=308 #lalt
Y_1=304 #lshft
L_1=122 #z
R_1=120 #x
START_1=49 #1
SELECT_1=51 #3
LEFT_1=276 #left
RIGHT_1=275 #right
UP_1=273 #up
DOWN_1=274 #down
QUIT=27 #esc
I added the following for player 2 without any luck:
#player 2 keyboard controls, disabled by default
A_2=97
B_2=113
X_2=115
Y_2=119
L_2=999
R_2=999
START_2=50
SELECT_2=52
LEFT_2=100
RIGHT_2=103
UP_2=114
DOWN_2=102
Any ideas why 2nd player not working?
Thanks