| This level is hard!
This level is rather difficult. It can challenge veteran players and most beginners cannot finish this level. Most players consider it to be a hard level. Even elite players may have trouble beating this in one attempt. Good luck in beating this level!
In this level, the first half is easier for the Runner. If you use her, just try to do high jumps between rings, since the tile size and the gaps are huge. But in the latter half, it is much more tricky, there is an extremely large gap, and you need to jump on a large ramp in order to reach there. You should try to gain as much momentum as you can and run onto the ramp (by not jumping and keep staying on the ground), but it is hard since there are holes and boxes blocking your way on the platform. Just try to dodge them and run on the ramp, do a high long jump and try to reach the end.
Using the Skater is much easier during the latter half of the level, due to his tremendous speed, but the first half is trickier. You need to land on the narrow platforms, while not falling into space, this can be quite a challenge.
Here is a brief description of the cutscene featuring in this level. The official page can be found here.
This cutscene was actually removed and replaced by dialogues. Down below is the cutscene version. To look at the updated version, you can still go here for more.
After beating F-3, a cutscene starring the Duplicator and Child will begin. The Child says that he calls the F-Tunnel "The River" and explains that it is a "thin blue line on the surface of the planet." He continues saying that rivers are really wavy, like the tunnel, and he saw one in a book. The Duplicator says that books are fiction, and the Child replies with, "Yeah, Yeah."
- When you unlock the Bridge Building minigame, one of the boxes is shown on the Galaxy Map to be in this level, but when you click on it, you are playing as the Skater on Level M-5. The reason for this is unknown.