The recent thread about Black Mesa and its various community-made engine upgrades reminded me of something I've always been curious if Source could do, given enough coding skill and access to the source code: Seamless map transitions. Yes, yes, I know, Source is like the only engine on the planet that still stores its level data as discrete maps, yadda yadda... Don't care. My idea is, the engine would somehow (and this is the part where I'm the fuzziest on the hows or even ifs) be modded to hold two maps in memory at a time, and swap out the one the player isn't currently in once they reach a certain point. Then the maps could be linked using a pair of brush entities similar to world portals. To keep memory use from doubling, the maps themselves would be smaller — a manageable option since you would no longer have to keep the map count low to minimize loading screens. Portal 2 is an example of a game that could be adapted to this system well, since it's linear and has points-of-no-return between every map. What I'd picture would mostly involve splitting the elevators off from the test chambers as separate maps, and triggering the transitions at the exact moment the doors close behind you. And then maybe tweaking which ones make you wait for debris to clear out of the tubes before the elevator arrives depending on which maps take longer to load. Obviously it's a system that would have worked better if it were working before they finished writing the game. Anyone out there know enough about game engine tech to know if something like this would ever be feasible?