Specially when it comes to his elevator in blood1:
And then at the bottom we have this trigger_relay magic happening:
When I first played the map, I wondered why I hit the max_edict error but seeing that... yeah.
But the result is quite awesome, as you can see here in this video at around 0:15: What I didn't show in the video: The outer buttons, to call the elevator, even match the state of the elevator. E.g. if you press them, they switch to the active texture as long as the elevator is moving. This is actually quite interesting, because the buttons you see ingame are just func_walls and the real button is hidden inside the wall brush behind the fake button. I wonder why he didn't just put a 1 unit thick non solid brush over the fake button, that would work as well, wouldn't it? I didn't even know you could activate buttons that are "stuck" inside a wall. Thanks god I'm currently just trying a simple elevator with 2 doors, still gonna be a pain to get working I guess. But I found this tutorial which is helpful: https://twhl.info/wiki/page/Tutorial%3A_Elevator_Doors_that_move
Edit: Wow that tutorial really is helpful, I guess Richman didn't knew about env_global.
He basically uses 4 doors for the elevator on each side, and then another pair of 4 doors on the outside so that's why all the path_corners.