It does not look very complicated. Can you post a schematic and clear picture of the front and back? Is that same board used in other more common games?

It looks like someone already may have had a go at it once. The TI chip is in a socket. The board connector pins get broken solder joints too.

Nothing stands out visually.

Check / replace the lm339. If PAL/GAL code is available that's a non invasive place to start since both chips are in a socket. They are sometimes protected from being read back, but there are some inexpensive burners that can test and program a compatible chip. 16V8 GAL are still available.

Some of those TO220 looking devices look like they have five legs or are just have the leads formed odd.

If the chip code has been dumped (sounds like it has from your link) it is trivial to make a new one made. So don't worry about that. In fact that might even be a good case scenario as it could be fixed without heating up a soldering iron.

This chip should work and a TOP3000 burner can program it, i've done the same chip for sound boards.

https://www.digikey.com/en/products/detail/microchip-technology/ATF16V8BQL-15PU/1008412

A couple of the solder joints look dry or broken. Could just be shadows, but worth checking.

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