A serial board or game controller board for use with the Bridgeboard?
Shouldn't be a game controller board - PC joysticks are 15-pin D-shells and a completely different standard. Might be serial, though, but I dunno what the RCA connector would be in that case. If we had a higher-resolution photo we could check some of the IC numbers and get a better idea - dh1, do you have a better photo?
I'd almost guess it's some kind of system-on-a-card with Atari-style joystick ports and composite video out, particularily with the sheer number of ICs present, but the only cards like that I can find on amiga.resource.cx are Atari ST emulators, and none of the listed boards look anything like that...huh, now I'm really curious.
