Sounds interesting, but we'll have to wait and see if this becomes reality (whether it be an official ZUN work or fan game) or if someone starts creating such a game using DNH or other language. I'm not betting on the former, though, seeing as Sakuya has been put in the backlog since SWR.
One thing that's likely with such a game, though, is that instead of CTRL the C button would be used for rapid fire just like in GFW.