The trick is to put into your mind what kind of movement should the player have while trying to solve danmaku.
I mentioned that I cheated, but I did because I found a safe spot, with that info in your mind you could make a shield that slowly follow the player, making them unable to stay into one spot, if a player is forced to move, either because there's an enemy object following or a shield that blocks / needs to be broken or loose bullets that aim to the player directly, you can actually put that into play to force different kinds of movement.
Saying that, I preffer to have different kind of mechanics that make me think fast, rather than a deadly danmaku, its more fun that way, good luck with your next projects!