Thank you! That was a great idea, now movement on slopes is smooth!

How I've done it: Created the slope with level block, and in it's surface settings, set 'Flat' instead of 'Shaded' for all sides (so it won't drop shadows) and after that I set it's FLAG1 on. And then I used 'set(camera, NOFLAG1)', after all that slope is completely invisible!

Edit: updated download links (previous post + first thread post), with version where I've added slope. Still looking for more feedback, bugs are welcome!

Best regards!