Unvanquished is an open-source FPS game featuring team-based strategy and RTS elements, pitting humans against aliens in a futuristic setting.
https://forums.unvanquished.net/
A recent commit added a spawnflag to path_corner which makes it stop trains. Simply set a path_corner's spawnflags to 1 to use this feature. (This won't work in Alpha 42, build from source for now.)
This simplifies elevators and togglable doors a lot - they can now be constructed using only 2 path_corners. Here's an example.
Nice 
FYI, I didn't test the patch very much before it was merged in, so tread with care. I'm not sure what the code is actually doing.
There are some other entity hacks I had planned but my summer has ended up being a lot less productive than I had hoped...
What other hacks?
Supertanker, what did you just do to ECEC, the elitist club of elevator copyc creators?