I loved lightgun games on the old systems, and I think the Sega Saturn's Stunner was the best hardware of the lot. The obsolescence of CRTs pretty much killed the tech, but the gameplay style has made a bit of a resurgence a couple times with the advent of the Wii and VR.
BNC Feed-Through Adapters (with Terminators if needed)
I'm kidding, I'm kidding!
For anyone too young, this was how you made gaming LAN parties in the early 90s when there was Doom, Doom 2, Duke3D and Quake 1 to play. It's a switch- and hub-less network connection where every PC is literally connected to all others in one line which is fed through each PC. Making your connection extremely sh!tty if you were on one end or someone between you and the other guy had a terrible PC or had to reboot. Well, actually it was generally sh!tty. This problem went away completely when switches (even just hubs) became commonly available / cheap for consumers.
I do miss LAN parties though. Online gaming is also great but it's just not the same.