A friend of mine and I managed to get Black Mesa’s multiplayer mode working on SP maps. I thought a Co-Op run of the game would be nice, since the NPC’s, scripted sequences, object grabbing seems to work. Everything works fine, but its not very stable and you can get a lot of permaglitches:
Only one player can get the suit;
Some doors close really quick after the player, so you can end up trapped;
If one player dies, he will respawn in some sort of “Spectator Ghost Mode”, which will make him invincible and he wont be able to do anything except walking.
Also, the game is pretty laggy. At 50ms ping you might start teleporting for a second, and the object grabbing/moving/throwing is laggy as well.
Anyway, we could give this a try, so if anyone wants to try it out or just mess around - contact me, and we can play it (if I get these ports working, unless you want to host the game). Its very buggy and I doubt if its even possible to finish the game, but its fun to play around in it.