It’s been said before, to no avail. People have tried to recreate them to no avail.
Seriously, I miss the UTPortal actors! They could do some amazing things; it’s sad to me to think that if Alexander Bruce had started with UE4 instead of UDK, Antichamber would never have been possible.
I’ve been thinking a lot about portal systems lately; I know that non-Euclidean geometry comes across as gimmicky and/or just a tool for making shameless Portal clones. But I’m doing a game based on arenas and I’ve been thinking back to stuff like Star Fox 64 or Xonotic, and creating arenas that cycle endlessly as a way of minimizing corner-to-corner travel time.
The point of which is to say, the ability to create “impossible geometry” has more uses than as a gimmick. Used subtly it can create a lot of interesting and useful tricks that enhance a game, though those uses won’t ever really be incorporated into games when it takes months of effort to try and get something the remotest bit functional up and running.