Oh man, I totally understand. I had okay success with one game and I think it's because it got the attention of the community of one game due to it originally being a fangame of it which evolved into more. The art style and movement system is very close. r/RotMG is where I posted with most success. I created a Discord server and posted it in bullet hell game subreddits. I got posts removed a couple times but it was worth it. My Twitter hasn't had much traction yet.

I'm not sure what kind of game is already like this, I think you'd have to do some searching to find out and post it as a "fan game" or "inspired game" on there maybe. Also try posting it on GameJolt. Maybe you can find YouTubers to play it, I'm not sure how to do that yet. I think it will be helpful to post more gifs of the game for sure, and create a build to make a higher-res YouTube trailer of it. I would post a WebGL and downloadable demo if possible. That's something I'm working on too.