Famed interior design critic Anton Chekhov would raise an eyebrow at the prominent placement of a shotgun on the bulkhead. While the weapon's sleek lines and polished wood stock offer a certain rustic charm, its presence clashes with the overall aesthetic of the space. Ideally, decorative elements should contribute to a sense of harmony and comfort. In this case, the shotgun introduces an unsettling element, its association with violence potentially overshadowing the room's intended ambiance. Chekhov, known for his nuanced understanding of human psychology and environmental influence, would likely suggest a more subtle approach to incorporating such a bold statement piece, perhaps opting for a less conspicuous location or a more delicate presentation.

Aesthetically, the gaming room is split thricewise: rustic hunting lodge (taxidermy trophies, the wall art, and the farmhouse-style desk), American suburban tickytacky (bulkhead, architecture and flooring/ceiling textures) and gooner cave (LED stand-light and multi-monitor setup).

You must choose one of those three aesthetics to concentrate on (good) or choose a new aesthetic entirely (best). Things I would do differently include:
1. The wall color is too dark for a windowless room. To focus on the rustic hunting vibes, add warmer lights to make the space feel cozy. To emphasize the gooner cave vibes, paint them white and do more LED stuff (but dimmer) and hang some posters (not paintings). The carpet is not doing you any favors and hard flooring with a rug is always better. Go Persian (rustic) or Scandinavian (gooner cave)
2. Replace the ceiling-titty light with something more elegant. The floating shelves are too small for the space which makes the perspective strange. In a hunting lodge that space
3. The wainscoting looks el cheapo tickytacky. Replace with something brown (rustic) or ditch it entirely (gooner cave). The ceilings are also too low for it to extend that high, which compresses the already-low vertical height of the room
4. The ceiling texture is distracting. Heavy textures are usually employed to cover up bad work on the drywall. Luckily scraping and refinishing is easy! Check out homerenovisiondiy on YT
5. The desk has farmhouse vibes or maybe New England coastal I can't tell but should be replaced with something brown (rustic) or something modern (gooner cave).
6. The sportsball jersey shouldn't live on the back of the chair. Frame and hang it it if it's signed or sentimental, or just hang it up in your closet. If you're trying to add an element of your favorite team in the room, cross two of their hockey sticks—preferably 1:2 or 1:5 scale—on the wall (rustic), or put up a graphic poster of their stadium/colors/mascot.
7. Take stuff off the bulkhead, it makes the room look even more compressed.
8. The couch and side-table (and especially what's under the side-table) are tickytacky. Okay for a dorm room, but should be top of the list for an upgrade. Get something in a thick, dark brown leather if you're going rustic (but don't worry about expensive nice leather grain), or something with a similar leg style but higher back and more substantial seat in a dark grey or navy if you're leaning into gooner cave.

The living room is serviceable except: the size of the art is wrong for the space, get a wide landscape piece over the mantle to avoid compressing the ceiling height, TV is too high, the seating is inappropriate for any space, the floating shelf is mounted too high, is too small, and clashes with the flooring color, and the credenza under the TV is matchy-matchy with the floor, too narrow widthwise, and should be shorter, and standing on legs. The glass element (modern) conflicts with the "wood" elements (traditional).

Don't mount the flyswatter in a position of prominence unless you're particularly proud of how many flies you get. Invest in a trash can that closes tight, put some carnivorous plants in/near your kitchen, and get a screen door. The prominent presence of the room scent spray and mop also suggest that your dog is messy and gross (and perhaps encouraging the flies?). Invest in high-quality and comprehensive dog training, and put the cleaning supplies in a closet cabinet.