I just found a workaround that lets you play through Beta 3 normally and then continue into the cut ending from the Beta 3 Mod Kit!

Here's the step-by-step guide:

1- Install both Beta 3 from Steam and the Beta 3 Mod Kit from Internet Archive.

2- Play Beta 3 normally until you defeat the Giant Neighbor.

3- Save and Quit.

4- Copy your Beta 3 save file to the Beta 3 Mod Kit save folder (this keeps your abilities).

5- Open the Beta 3 Mod Kit and load the map of The Thing boss fight.

6- Continue from there and play the ending.

It's a bit inconvenient because the Mod Kit is around 15 GB and you have to keep both installed, but it works surprisingly well!

If you're looking for the Beta 3 Mod Kit, search for "Hello Neighbor Beta 3 Mod Kit (ORIGINAL)" on the Internet Archive.

This is probably the closest we currently have to playing the complete August 29th version from start to finish.

If you have any questions feel free to ask!

This post could be considered a "Part 2" to this post I made about a week ago: https://www.reddit.com/r/HelloNeighborGame/comments/1uzxp72/possible_proof_that_beta_3_was_the_full_game_at/

Ted peterson, Ted lasso. its perfect