The game will not likely be receiving any content updates (on any platform). Numeric has stated that he considers Ep0 and Ep1 "complete". There may be bug fixes released, but he's looking to focus on Ep2.
Recent community posts
The steam copy is legit, the dev had issues initially getting it approved by steam, and had some hoops to go through (like submitting under a new name).
All versions (steam, dlsite, itch) should contain the same content and be patched with the same files/methods.
Oh my bad dude, I have no idea what's up with the new patch. When I downloaded it, there was a link right next to "UTW Patch.zip70 MB" and it downloaded a single archive (which extracted without issue). I don't see a link anymore, hopefully ShadyCorner will update soon with a fixed file or link. If not, I'll upload the files I have and send you link (my files are for ver 1_2, latest is 1_5, which is why waiting for Shady is a better idea).
If you're getting an error when extracting the main game files, follow the instructions in this post:
Winzip sometimes has problems with multi-part archives. If you follow the instructions above and still get an error, try a free archive utility like 7zip or Winrar.
Go to where you extracted the game files, then navigate to:
Extract the patch to this location. Once done, the Paks dir should contain:
Try the patch in ver2 first. If the game crashes at start, delete the _0_P.pak from Paks, and replace it with the copy in ver3.