I announced last week's huge find on the Discord but, I thought I should post it here. I found the source code for the web demo version of the game, which has allowed us to confirm and disprove certain aspects of how the game works. Unfortunately, the demo only contains a fraction of what the full game has, but a lot can be and has been deduced from looking through this code.

My writeup on what can be deduced from the code (WIP): Google Doc

Link to original SWF (Shockwave Flash) files (pvz_9_15.swf is where all the game logic is): Web Archive link

Link to all the files that can be extracted from the SWF: Google Drive link