I'm not sure if kscreenlocker is the best place to file this bug because it really involves potentially three components: the screen locker, power management, and device I/O.

OBSERVED RESULT

I occasionally like to play games on my computer, and when I use a joystick or gamepad (e.g. Logtech F310, Xbox One controller) to play a game, KDE apparently does not consider joystick input to be a kind of activity which lets it know that a user is still interacting with the system. Thus, if the screen locker is enabled, the screen locker will activate even while playing a game unless I occasionally move the mouse, touch my laptop's touchpad, or press a key on the keyboard. Likewise, if the Power management is enabled for things like dimming the screen, turning off the screen, or, presumably sleeping/powering down the system, it will activate after the specified time period has elapsed even if I'm playing a game.

EXPECTED RESULT

When playing a game with a joystick or gamepad, the system should register gamepad I/O as activity which keeps the system awake and prevents power management or the screen locker from activating.

SOFTWARE/OS VERSIONS
Linux: kernel 5.4.28 / Manjaro 19.0.2
KDE Plasma Version: 5.18.3
KDE Frameworks Version: 5.68.0
Qt Version: 5.14.1

ADDITIONAL INFORMATION

Although I'm reporting this bug on the versions specified above, this has been a longstanding issue with KDE/Plasma 5, and I have observed it on other Linux distros and FreeBSD, so it appears to be independent of the platform it's running on.