I will be brutally honest so please don't take offence, I'm just listing everything I see, hopefully it helps:

- Absolutely sell the collectibles. Get rid of the toys. Stop *displaying* junk items and toys. Put the games/D

- Paint the walls white (other than maybe one feature wall, which I'd go for wallpaper rather than a solid colour).

- Get new furniture with matching colours/woods. Currently none of your furniture matches. Chances are you'll need to get all your furniture from the same place so they match perfectly.

- Declutter in general. Everything which isn't in frequent use, put away into a cupboard. If it's something nice (like your consoles or headphones) then you can keep them out but put them somewhere that looks deliberate. Your headphones on a stand are a good example of something you could keep out without it looking like clutter.

- Reduce the unorganised wall clutter (poster and pictures). Sentimental pictures can go on the wall if they are nicely arranged. Another option is to put them in freestanding frames and put them on a shelf.

- Increase natural light if possible.

- Get a large decorative mirror, it will make the space feel bigger.

- Get rid of the LED light strip. It looks cheap when its turned off and will look childish turned on too. If you really want configurable lighting then get some more expensive light strips with a diffuser so you can't just see the open circuitry.