Fell into area underneath first level in Justine

[Apjjm]

There's a way down by simply running against one of the welders on the entrance to the room with the cells (literally just at the spot where you gain the ability to run). The method is the same as the trick in my with-glitches speedrun (You can also use that spot to get out of the map, and then navigate form there, too, probably).

Incase you are wondering how this happens, consider the following scenario. The player is treated as a "cylinder" for the purposes of collision detection. Now lets assume that player attempts to move into a wedge-shaped corner. Consider a wall of the "wedge" - it will flag a collision and attempt to "push" the player out via the shortest route. Because the player is a cylinder, this shortest route is a line from the centre of the player to the point of the player that is embedded deepest in the wall. Following? If not, draw a diagram.
Let us consider what happens now, if we apply the right force along this "shortest route" we should push the player out the wall - that should fix it right?
Well, the player is pushed out of the wall, but the "push" doesn't really impede the motion of the player from going back into the wall next frame. In the case of the wedge shape, we won't be impeding the forward motion of the player that much (The narrower the wedge, the more the push approaches being parallel (useless) to the motion of the player).
But wait, it gets worse. The push actually displaces the player more inside the other wall! So you start to get this oscillation between being in and out of two different walls, and the more you run forward, the more this oscillation gets larger, and larger. Eventually, you will run enough to be push far enough into a wall, for the minimum distance to just push you out the other-side. Congratulations. You just breached a wall.

Obviously, this depends on the thickness of the wall, and the angle of the wall, and what I have described is a simplification of what is actually going on, but you get the idea.

Oh wow, I digressed quite a bit there. Oh well