Nowadays, when you create a map, there is almost always an intended gametype that will be needed to be made to get the experience just right. But, since forge is its own feature, and custom options is its own feature, they are distanced. To make a gameplay experience where the map and the gametype are married together, you’d have to constantly enter and exit each mode to refine your experience and get it right, and obviously that sucks in a lot of time that you can use to refine/modify your game.
It would be a lot nicer if during a forge session, you can create your own gametype, and access all the custom options available. That’d mean while you’re making your map, you can make and adjust the gametype that goes with the map, on the fly, with access to a little menu window, just like the objects menu. And the custom settings will be adjusted (whether it’s immediate, or after restarting session) for on the spot testing, without the need to start a custom games session.
Like chad said, “custom games and forge go together like peanut butter and jelly”, so there’s nothing better than to just put them together. Forgers and gametype makers already have a heavy burden to carry, so it’s best to make things the most convenient they can be.
And if this suggestion/idea has already been posted, I apologize.