ZDoom

Alright, no problem, it can be done with a decorate expression check in any case. Thanks for looking into it anyway!

There's [i]just[/i] one tiny little problem here: The entire code to check for stuff to use has absolutely zero concept of height. It's not something that's quickly added without potentially causing secondary issues.

[quote="ZZYZX"]Actors can switch on use (+USESPECIAL, either special or THINGSPEC_Switch)

Not sure if this is the case for the author though.[/quote]
Yes this is what I'm talking about https://zdoom.org/wiki/Creating_decorations_that_can_be_(de)activated
These actors can currently be activated regardless of the player Z axis distance from their position.

Actors can switch on use (+USESPECIAL, either special or THINGSPEC_Switch)

Not sure if this is the case for the author though.

A switchable decoration is just a dumb thing. All actions will normally be done by some external trigger, so you'll need to change that to handle the height - or use a script instead of a direct Thing_Activate invocation

Would it be possible to add a flag or something to check the player's height when activating switchable decorations?

For example, right now, you can toggle a lamp that's on a tower above you if you are in front of it in plan view. It would be nice to have something similar to the switch height check when using these decorations.