The gaming should be in the "Treat As" list, where Windows System App, Trusted App, and so on are. So if D+ shows an alert, you can treat this application as game.
I think that's easy, and not so dangerous then putting CIS to Training Mode, where every app can do what it want, and not only the game.
I don't know how often i mentioned it here in forum, but I don't think that a Training Mode is any kind that should D+ have, cause Clean Mode is much better, and it's SAFE.
What kind of D+ setting is it, to learn everything. Cause that means, learning every bad action(also of malware), too. Don't think that this is the sense of an Security App.
The Game Mode rule also should learn the specific action, and not only wildcards, which can't really be edited, cause then you will nearly block everything again, and the game crashes.
And treat an game as an windows System app would give it so much rights, that aren't needed for a game.
And why is this Topic once here and once at Firewall Wishlist?