Its mostly because DOA is considered kinda a sexual game and because most videos on YT of the game are basically bikinis or skimpy mods they probably put genuine videos of it in that skmpyame boat. Its hard to explain, id go broswer and not sign in and go on YT to see if your channel is up on restricted mode
I just checked and my channel has no restrictions whatsoever. Like did you get restriction yourself? YT wouldn't put anything on restrict unless you try to add porn or breaking their guidelines/strikes. There has to be a reason for it and having "DOA" as the game itself is not a reason because it's one of the listed games.
80% of my Youtube channel consist of DOA. DOA isn't the reason why it's restricted. Restriction is a whole new use of words so the only thing I can see here is getting a strike within the guidelines and "limiting" your upload content. Is he talking about that? because "that one" is real by the way.
Well if it's nude mods then I can totally see why they put it on restrict. If it's trying to link for malicious downloads or cracks then that's another way of getting a strike or restrict. Youtube's rules are somewhat nuts, but they are not "that" nuts to just stop by you and limit your uploads.
There can be many reasons. Verifying your youtube account is a necessity and that in itself limits your content and uploads because Youtube needs to know if you are a genuine account. Uploading videos more than 15 minutes long without verifying your account is another limitation.
Breaking rules can lead to strikes for termination or using music that's copyrighted that you don't own or got permission is another.
And lastly, the harsh one. Monetization. If you have this turned on, Youtube will be up on your behind instantly if you are getting net revenue off it along with using music that you don't own. I have this turned off because I have no interest in making money off it.
I don't think DOA is the reason if you are uploading standard gameplay. Anything else outside that barriers can't say, but there might be a different reason.