We are doing the same thing with our "barn". It's about the same size I think. We just bought an excellent condition 3 pc. slate pool table for $100 bucks last month and got that set up out there. We already have a room in the house where we put all of our mounts and outdoorsy stuff, but the barn is now called the "man barn". Since I am "one of the guys" I'm allowed in it lol...
Under our pool table, we put green indoor/outdoor carpet and framed it in (sounds corny, but it looks pretty cool for our purposes), we plan on painting a football field on it with the Detroit Lions endzone. On the wall that the "football field" butts up against, we are making a field goal with pvc pipe and will be putting a projector out there to project the games between the goalposts. On the other end of the building, hubby and his best friend are going to be building a poker table and there will be a small bar. We are building a pub height "bar" around the half of the room the pool table is in and will be putting stools under it all the way around. We also will be getting a ping pong topper made for the pool table and will have a dartboard. We want one more "game" in there, but can't decide if we want one of those shuffleboard games (played it at Dick's, pretty fun) or if we want to get an older edition arcade style Golden Tee game... guess time will tell, depends on what kind of deal we can find.
Those kind of "man rooms" are fun. We have rafter ceilings with plywood on half for storage. I believe hubby is going to close it all off with plywood or drywall and insulate it. We also have a garage door we will be taking out of it to aid in the insulation process. Not sure what we want to do for heat yet, I was actually thinking one of those electric fireplaces (no gas line run out there) would be sweet for in there, especially during football season when the snow is flying, and for $300, it would be a nice touch. Oh, and hubby has to have the sign "Hot beer and cold women" or something like that...

Sheesh... men! LOL