Im not sure if people from the forum know about it, yet I will share this anyway for people who doesn't.

Knytt map is made of screens. 7th row is secret and the deepest one. We think that it's impossible to go deeper, there is no passage... there actually is a single one!
https://i.imgur.com/Lumcm1h.png
Im sure many of players already tried to get there, it's extremely difficult but I have to tell you that it's possible. You could just change velocity or get a balloon in Settings.ini to do that easily but you must know that you can do that without messing with this file, only with codes. I know that because back when I was much younger I did it successfully for once.
Now to not torture myself with thousands of attempts, I gave knytt balloon and went down leading to 8th row! If you haven't knew about this then you must be very curious, it can be a bit disappointing so don't count for something spectacular:
https://i.imgur.com/GmZdcKS.png
8th row's screen is just a purple void (similar to Knytt Stories) where leaving screen from sides only make you return from opposite side (similar to Knytt Stories' warp system object) and falling from screen kills Knytt:
https://i.imgur.com/GUXKpg0.png
When you look at the map while being there, you don't see a lighten square below 7th row.