Not the worst Sega Game Gear I'd ever seen, but was already prepared for the smell of removing these old caps (the blocky rectangular black and beige things above). They stink of fish.
I recapped with surface mount ceramic caps, much smaller surface area than the originals, will never leak, and you can't mess up polarisation with them.
I did go back and retouch some of the soldering afterward, as I ended up removing the dead fluorescent bulb, and trying an LED backlight mod, which you can see below, running Golden Axe Warrior on Master system (I was testing with an AliExpress flash cart.)