It is all alone, accompanied by nothing but strange "machines" and depressing music. It is also crying. Has Mars-san simply burst into tears because it too is trapped on this strange planet, and it's helpless? Maybe the machines are it's countless ways to escape the planet.
Could this be symbolising an element of deep and utter hopelessness, being trapped, and unable to escape? Not being able to escape not just mars, but being that this is Madotsuki's dreams, maybe this is a realisation that she is trapped in her own mind?
Dapressing, emotional music can be heard in the background along with a hissing noise. Mars-san is crying. Machines are everywhere.
This can easily be put with other theories to suggest a possible reason why Madotsuki kills herself in the end of the game, because she can no longer stand being trapped in her own head.
Lolster1
It may also symbolize something tragic that occured around machinery. One theory says that the machines were meant to symbolize a subway. A sprite that didn't make it into the latest edition puts doors on the side of the wall after Mars-san which could connect to someplace else (Perhaps it would connect to the Subway section?). If this were true, then it could be hypothized that Madotsuki saw someone being killed on the subway. Mars-san could be a man whom she was afraid of (due to the bizarre appearance) but also sad and perhaps somewhat sympathetic to.