Can you tell us which types of games are u playing? About your requirement of gaming quality.
In general, which needs to pin point footstep (Fps and maybe some other), you should go for open-back since it has very large sound stage and anemic bass.
If you want to enjoy games with immersive sounds (BGM, gunshot, voice, etc) you better go with closed-back.
For music, it depend on your genre you listen to.
Personally, I would prefer open-back because I don't really like bass and play FPS a lot.
In some cases i need more bass, just EQ it with my usb sound card ( Creative omni 5.1)
You should try ATH-AD500x (~$65, price on amazon) (I use 700x), but remember that it totally lack of bass and no mic.