Welcome.
I'm happy to introduce the v1.1 update to Simulacrum. This patch introduces a number of bugfixes and clarifies some aspects of player progression through the story, as well as fixes compatibility issues with other mods.
While I'm not yet able to suss out the cause of Amnesia crashing on loading certain maps (apart from where it's due to an outdated installation), TiManGames helped me uproot the issue with Simulacrum conflicting with other mods, and so there should no longer be black/glass walls blocking progress in unpredictable places.
In the meantime, Bizzeplayn has been putting out some great playthrough videos on YouTube.
Since the whole spider encounter can and does get more frustrating than scary, the Pestilence dungeon finale has been smoothed out - the swarm will now gradually begin despawning after a short period of time, hopefully mitigating frustration without sacrificing the initial tension.