In the past weeks I've been able to add the following from the initial demo version:

• 15 new levels (levels 11-25)
• 2 new maps (tileset): The Office and the Backrooms (kinda)

- THE OFFICE

- THE BACKROOMS

• 2 new enemies (the zombie that can use doors, and another that can use both doors and ladders)
  • Ladder Detection Nodes for this third enemy
  • New raycast detection system because the movement for the third enemy is more complex than the first two enemies
  • New sounds
  • New particles
• Some gore/guts/infection stuff for level design
• Letters for the "portal" doors to avoid confusion
• Menu Screen background showcasing the different maps in one setting
• New file saving/loading system
• And of course optimized hundreds of lines of code and fixed hundreds of bugs lol

Here's the current tileset: