Its probably not possible, but I'm not sure why a patch would have removed it. If your playing single player only you could roll back to patch 1.62 and hope it was patch 1.64 specifically that took it out if it matter that much to you. The only single player fix is for the docks level but if you go the correct path that shouldn't be an issue.
The thing is though, I only looked up the patches after I got stuck on that very level XD.
What was the right way to go? The only way I found was to go into the area full of shipping containers. That's when it used to not open the next gate even after you've killed everyone.
This wasn't the GOG version of the game, was it? AFAIK, the GOG version is already fully patched and you shouldn't need to apply anything to it.
No it wasn't, I just heard of this place on another site and they said it was good for help with older games (hence the name I guess).
Anyway, I think I'll just leave it as is anyway, thanks for the help guys.
In regards to not being able to finish a level, I had something similar happen to me on the Opera level. After killing all the enemies, the checkpoint would not appear. The compass was indicating an enemy above me but I could not see any enemies and the doors were all closed to the stairs.
I finally got to the far left of the stage from where I could see an occasional flicker of a sword on the third floor balcony. A samurai ?? ( could only see the sword tips ) had spawned but never jumped down. He seemed trapped and the swords would move left and right a few feet. I lobbed stakes over the rail until I hit him which immediately made the checkpoint appear to the right of the stage. This was the GOG ver 1.64 game.
It may be that the Docks level has a similar bug?