I do miss the two-player mode of Lemmings on the Amiga. Amiga could support a mouse in every port, so you could both use a mouse while battling each other. One player needing to use a joystick on ‘every other platform’ (which for Lemmings, was every other platform in existence at the time) was vastly inferior.

Basically every other computer either only supported one mouse, or all mice moved the same pointer.

Not saying that this is a generally useful feature, and networking has improved to the point where split-screen games are rare, and in an era where most games have console ports then mouse-control multiplayer games are unusual, but you know. Niche usages.

Xorg servers starting from version 1.7 have a feature called “multi-pointer”. Basically it allows to have multiple mouse cursors (each with its own keyboard focus) on the screen and control them with separate physical input devices

1.7 was released in 2009.