1. To exit from M34 it's require to find 2 skulls. On the video you can see how to grab all 3.
2. There a plenty of secrets here. I've focused on two major onces, which will allow you to play chess and mahjong with arch-vile. It's not easy to make access to them, as well as in addition to it require a keycard, which can be found in two places.
So at the end point it took long enough to figure out the things - M34 goes as long as ~ 1:39:00 on the video without cuts, due to a lot of rollback and attempts.
Games can be seen on ~ 3:14:00 and ~ 4:12:00.
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