Introduction
The M-Tunnel is a side tunnel that branches off of Level 33, along with the Box Storage Area. The tunnel consists five levels which can be played with any character.
Suggested Characters: 
Gameplay
In this tunnel, the colors of normal tiles are random. Moreover, the levels of this tunnel mainly consist of jumping along platforms, so most of the time the Runner is the preferred character. But there are also big chunks of crumbling tiles, which normally fall away once you step on one, because they are all linked.
For all of these levels, the Child is also a preferred character due to his advantages in environments with large patches of crumbling tiles. There is also an achievement available to him.
Achievement
There is only 1 achievement exclusive to this tunnel.
Follow the Gray Brick Road
Suggested Character:
Use the Child to beat Level M-4 in only one jump. (Disclaimer: the tiles are not actually bricks.)
Trivia
- There is only one box in this tunnel.
Levels
| Levels | Images |
|---|---|
| Level M-1 |   |
| Level M-2 |   |
| Level M-3 |   |
| Level M-4 |   |
| Level M-5 |   |
Plot
There is a cutscene in this tunnel. More information can be found on the Story page.
Insanity
After beating Level M-5, a cutscene will begin in which the Duplicator is watching the Runner's attempts to reach a tunnel in the distance. She kept trying, but she fell short every time. The Duplicator asks the Runner if she has gone insane, but the Runner denies it. When she respawns, the Runner notices that the Duplicator drew on her map. The Duplicator says that this is to "commemorate the moment" she has gone insane, before the Runner finally makes it past the gap and reaches the F-Tunnel (The River).
Difficulty
| Sandbox |
|---|
| Very easy |
| Easy |
| Not too easy |
| Almost medium |
| Medium |
| Over medium |
| Above medium |
| Fairly hard |
| Hard |
| Extra hard |
| Insanely hard |
| Hell |
Difficulty of the Levels of the M-Tunnel
| 1 | 2 | 1 | 1 |