I always thought IREM’s LED Famicom carts were cool. Also a good way to see if your Famicom is still receiving power if it’s not outputting video and you don’t have a multimeter immediately handy.
Here’s Deadly Towers, the only one I have at the moment.
While this isn’t a special piece of hardware, it was still a cool find. For a while Hector’87 was trending on my social feeds. During one trip to a Book Off around that time, I found this cartridge. Covered in Hudson related stickers. I guess whoever owned this was a Pro STG player.
It felt very personal. No idea why it was there. Maybe they reached their goal and decided to finally move on.