DreamRealm

You can Download DreamRealm at the download page.

When you start, you are assigned to a certain outpost.
You start in the lowest rank. You are there to
kill, murder, and destroy all DreamDemons.
And DreamDemons are here to destroy the world and all of humanity(and, of
course, all dreams).
You can even fight the DreamDemons with your friends online. And
advance in ranks and get new weapons and guns.
Well, this is what it will be like when version 1.0.0 comes out.