After a few hours of searching I've concluded that my Game Gear (games, and accessories, etc.) is lost.
Searching online I have found
a Game Gear cartridge that someone has depopulated, scored aggressively and had the gall to sell to a collector
- maxim smspower.orgPinouts
a collection of information concering the SMS/GG cartridge pinouts, signals and logic
I transformed and traced the cart manually using Inkscape (didn't bother fixing the trapezodial deformity since I the whole pcb isn't visible, one square edge is good enough.) Resulting in this image:edit: new trace
Then I matched the pins from the cart to the chip using the pinouts from SMS power, in Eagle.
!WR looks scarry, but it is actually an indicator whether or not the CPU is writing data to the bus. I think that it is being as a chip enable to reduce bus collisions.
If you could post a scan or reasonably high-res photo of both sides I would be able to reproduce the PCB and could identify the remaining connections if they are present.EDIT
There also used to be a geocities page about re-flashing the roms in the early GG cartridges (EEPROMS!) after they erased themselves. I know that a few of my games needed that treatment when I put it away.
looking only at components with ligic compatible data and address lines
... Ack food.
Another mystery solved, the cartridge was designed for one EEPROM and substitution at the factory must have introduced this problem; it only appeared in the early carts either because of a standardization of part, or mfg's got smarter about the board design.edit: inserted new trace from clear photo, and note how close pin 31 (commonly !WE) is to still being pulled to ground.