Please say which game it is. Did you ask the game's creators already?
Edit: also, this category is for questions about Itch, not for help with this or that game.
Viewing post in Access Denied when playing a game
Like No Time To Play already said: This sub-forum/category is for questions about itch.io. If you require help with a particular game you should ask the developer of that particular game that game’s developer would be the person to ask. Since that developer seemingly can’t help you, you’ve done everything you can in that regard. You can still wait try things on your own, wait for and try out a future update that might fix the issue or hope for another player of the game to recognize the issue and reply in the thread you’ve created on their forum. Maybe find a forum for Windows 10 enthusiasts on the internet?
As far as I understood them, No Time To Play’s remark about the lack of information you were giving was aimed at you giving that information (in general) when asking others for help with these kind of issues. (Since other games run for you, it seems like the issue has nothing to do with itch.io or the itch app in particular.)