I'm a gamer who has played many games ranging from arcade type games to modern day games. (Only 19, I'm a young but old gamer, lol) I've racked up countless hours gaming and to be honest I probably should've used that time wiser but nevertheless I can't reverse the past.
Anyways, as a member of NZ eSports Federation as well as an active gamer, I will say that in my opinion it really depends. If the game is causing you to feel like sinning or wanting to sin then yes, in a way it is affecting you and God might not be happy that you're playing a game that will eventually lead to you sinning. For example, someone that is a Christian might suddenly turn dark and want to do a real life GTA. (Highly unlikely but still possible)
If you are able to know that a game is a game and that it is not real and you know that it won't affect your relationship with God and you feel that God wouldn't be upset with you if you played that game then by all means, I don't think you'd be sinning.
Because we are determining whether violent games is a sin or not, there is no part of the bible that says, "Violent Gaming is Wrong." as obviously gaming didn't exist then. So you must find parts of the bible that speak God's Commandments and relate them to the game you're playing. For example, obviously if God said, "Do not commit murder." this would mean a human killing a human in real life. If you're killing a virtual avatar, it's not a sin but if you gain a mindset to kill a human based on killing an avatar, then it'll definitely become a sin. (Again, you'd have to be mentally unwell or just a really disturbed person to do such a thing as I personally don't believe games make people violent because if they did, this world would've ended years ago)