You know you're a Submachine addict when...

[Boingo]

Same here.

[The Kakama]

You start looking for red and blue marbles in random places.

[Sublevel 114]

When you collect ground dirty stones, thinking that they are key stones...

[bender]

when you try to shoot portals from your severed arm...

[Rooster5man]

When you think your Laptop's making Submachine noises when it's just its CD player trying to process the CD.

[Sublevel 114]

when you take down planks from the floor, trying to find secret balls.

[WorldisQuiet5256]

When you try to figure out a way to actually get in the Submachine World.

Or wanting to visit the Kent Falls and write on a stone near one of the waterfalls "Murtuagh Arm was Here."

[ENIHCAMBUS]

You see the sky completely covered with white clouds and you think that Earth is in Layer 7.

[Sublevel 114]

when you make conversation with Mur.

[WorldisQuiet5256]

I'm lost, how does that link mean when you had conversation with him?
Its just his users page.
Most of the links there are blank.

When you start writing notes in your Black Dossier about things in the Submachine as if you actually been exploring the SubNet.