This is a template Unity project Omiya Games uses to start their game project.
In this Unity project, the following folders has the following roles:

Assets:
A folder required by Unity.  Contains assets used for the game.  See the README.txt in the folder for more details.

ProjectSettings:
A folder required by Unity.  Contains settings for Unity.

Builds:
A folder where its contents are ignored by Mercurial.  Typically where game builds are created in.

UnimportedAssets:
A folder that Mercurial versions, but Unity doesn't detect.  Typically where unfinished art assets are placed in.

Library:
A folder required by Unity.  It's contents are very cryptic and mysterious.  I wouldn't recommend touching it.
Ignored by Mercurial.

Temp:
A folder used by Unity.  Unity creates it when an editor opens.  I wouldn't recommend touching it.
Ignored by Mercurial.