We are currently trying to sell our double brick house. Our upstairs floors are nice and airy with plenty of windows etc, but downstairs is your typical rumpus/study/laundry floor with bricks walls (most of which have been painted a neutral colour). There are big sliding doors in the rumpus opening to the backyard, and one north-facing window. We are on a sloping block so the downstairs level is built pretty close to the ground and into the side of the slope.

At our first open house, 2 separate groups commented to the agent that they didn't like the feel of downstairs.

We can't really move the furniture etc (it too us ages to work out which furniture layout worked best for sale purposes) so I'm wondering if there's anything I could do to improve the "feel" of the room? Should I be buying some goldfish? Hanging some mirrors? Any suggestions?

it is rather vague what you are asking to address the situation - the first port of call should be your agent to find out what exactly the 'feel' they did not like. Maybe these were polite reasons for not proceeding?

Want to post some photos of the space, and we can see what is happening down there.

That would definitely help... esp from different angles