Due to the transition to the game's new engine, it was reported to us that files were missing from the game's archive, preventing play. After isolating this issue we can confirm that these have been addressed in this revised patch;
-We've resolved missing file issues that occur on the Giant Tree and other areas.
-We've fixed a progression bug in the Giant Tree.
-We've fixed a missing file issue in Pazuzu's Tower.
-We've fixed a missing file issue in Doom Castle.