downloaded Dark Room. easy enough it seems. Dark Room they.misled.us
first had to download MS .Net framework. just did it. okay.

Requirements

• Windows XP / 2000 / 2003
• .NET Framework 2.0

---------------------------------------------------------------so. it loaded full screen. "Esc" got me out. F11 appears to toggle in & out of fullscreen.

the arrows on the upper right of screen are for scrolling
I wonder why put there? why would you use those instead of arrows on keyboard, page up & down? is it in some way simpler, more like a typewriter? I dunno. using the mouse makes me want to be able to scroll by clicking on the screen and you can't. bcs that is the kind of interface this is an alternative too right?
weird for me to be outside a browser I guess.

NOTE: under Edit - Preferences
you can change the "Environment"
just as Writeroom's site says:
Your WriteRoom can stay green-on-black, or you can choose your own colors, fonts, and page layout. Scale up your text for easy reading. Show the scroll bar all the time, or only when you need it. --the 'scroll bar' disappears if you select "Hide Navigation"

[ Dark Room is a clone of the original WriteRoom that is an OS X (tiger) exclusive application ]

what I want to especially note is the preferences that were the default green on black.
the black is in the lower left corner.
the green is the one three down (in a column of greens which is three over, it is the bottom one).