I've managed to push a Propane Tank from before Saferoom 2, into Saferoom 2, and use it to skip over the train in the last section.

Possible to skip the saferoom entirely and get to the truck and gascan section, but unable to pick up the gascans themselves despite them being there.

You can also squeeze through the steel doors that open up at the start of Laby by the first sigil, but it won't let you progress and acts as if there's a fog wall.

I'll be testing some other suspected skips soon so I'll make replies to this post for archiving and looking-at.

While I haven't been very active in running or playing, I still love this game and the possibilities. I believe this game (and its sequels) are very able to be exploited to make it all faster.

The only trouble I continue to encounter is not to break the game, but to hit certain loading triggers that seem to only spawn after killing certain waves -- I wonder if there's a way to force these loads to happen...