I feel your pain, having gone thru something similar. First is there insulation going on those walls? If that is drywall with wallpaper then painted, then it is going to be difficult
to get the new drywall to match. May be an idea to take off all the drywall and start from scratch.

Keep the wonderful stone fireplace!!! Use it as your inspiration! Under the blue half walls, you say there is wallpaper with paint over? I would pull all off and start with fresh large sheetrock sheets. More work in trying to match the top & lower half plus lots of extra plaster work...plus you still have the icky top half to strip. Shouldn't cost that much more, if extra cost at all. You have removed carpet...so what kind of floor do you want? What kind of shape is the concrete in...could it be stained and finished? Less costly than putting down wood or laminate, but those would work for "rustic." If you stain concrete, choose browns, rusts, golds...you've designed sets so you know how that goes! If there are fine cracks, embrace them when painting floor...plus add some more "veining." Use tall thick baseboards...stain a amber warm honey color taken from the stone...or go dark like the beams above (don't remove he beams...they are making a comeback)...maybe add a nice crown at top. Pick a lighter shade for the painted walls if the room seems dark...or look at color like Benjamin Moore's Lenox Tan. About the bar...remove that mirror! And I would probably remove the doors, too. Do you still plan to use it as a bar for entertaining? You could add some upper cabinets with glass doors and put new doors to match on lower cabinets. All the cabinets could be painted black (& age the corners/edges with sandpaper & then stain those new wood areas) or another focal color. You could even rework the lower cabs and add a wine fridge below. New hard surface countertop a must...can't hurt quartz. Choose rustic furniture...include a variety of woods and stains...not matchy at all...or find flea market pieces and paint...again...think "stage." Traditional leather furniture...and find/buy/make pillows with your "theme" if there is one. Accessories can always add more "rustic" and be changed if you tire of them. Most expensive items make sure you love. This is from former TWHS classmate & stage crew buddy! Susan

http://houzz.com/photos/375608

Look at this link...hope it works. On the track of what I was thinking...adding some rustic wood touches...leather...but use plain paint...no design.

It looks as though Susan Nelson has things well in hand as for great advice. Just thought I would suggest if you haven't thought of it recessed lighting or tract lighting should you not want to be encumbered with cords for lights especially in the game area.

I am still learning this website and can't put images on comments yet! If you would like to see some examples of recessed and tract lighting just click on my icon and click the "Lighting" Idea Book.