first of all you need to paint the walls in light neutral color. it will maximize the space.
the second thing in my mind is the little red area... is it enough for the t.v? if the answer is yes then you can add 1 or two chairs on the wall where the tv unit is. " i would also move the deer head mounts there"
adding more additional light to that space is essential as well as colored accessories and cushions. a large horizontal mirror "with a thin frame" above the sofa would look nice too

Your basement is a large underutilized space and it has loads of potential. As suggested before you need to start with a lighter neutral paint color to give the illusion of natural light. I concur that the TV should go in the red niche area so that you can bring in additional seating. Your single unadorned sofa looks pretty lonely and its current placement does not allow for optimal viewing or conversation. Also consider a privacy film on the three windows by the pool table. I realize you need whatever natural light you can get, but the garage view is not attractive. Have some fun family photos printed in black and white on canvas and hang them in a nice grouping. You have lots of blank wall space. Make use of the nice table you have in the corner. With a comfortable desk chair and lamp this would be a great computer/homework area.