I just want to start off by saying that this solution may not work for all cases but I just wanted to share how I was able to solve this problem. It might help somebody else, though.
I got a new phone (Android, OPPO Reno 2F) and transferred all my data from my old phone (Android, Huawei Y9 Prime I think) into this new one. On my old phone, Cytus ran just fine. But on my new phone, it wouldn't launch. It would just say something along the lines of "Best enjoyed with headphones" then turn white and unresponsive. So, I searched the net if anyone else was having this problem and jf there were any possible solutions.
Sure enough, this was a pretty common problem. I checked the reviews on the Google Play store and on the Cytus Wiki and a lot of people had the same problem, yet there weren't a lot of answers. Of course, I first tried uninstalling and reinstalling it on my phone. I tried 3 times but it wouldn't work. I also tried resetting my phone, but no dice.
The first "solution" that popped up on my search is [this youtube video.](https://youtu.be/jMVKVHbva0I). To summarize, he basically says to go into your phone's storage and to access the game's obb file and launch it from there. Now, this would probably work if you had the obb file in the first place. But in my case, there was no obb file at all.
So, moving on to the second method. I tried to transfer the obb file on my old phone to the new one. I shared the obb file to my Google Drive on my old phone and downloaded it onto the new one (Also, I didn't unzip the file). I then moved the obb file to the Cytus folder and tried to launch it from there. Didn't work, because there was no option to open it as an app. Maybe I did something wrong here and it might work for someone else. Maybe you could transfer the obb file to your phone through a different method. Or maybe you need to unzip it? I'm not sure. Just saying, because someone might find this helpful somehow.
Now this is the final and successful method I tried. I searched if the problem was with Google Play Store itself (I searched this because several other games had the same problem as Cytus, they wouldn't load. If anyone wants to know, it's Tone Sphere and Lanota.)
Anyway, to cut to the chase, the tutorial is [here.](https://support.google.com/googleplay/answer/7513003?hl=en-GB)
I tried clearing the cache and data of the Play Store and restarting, but it still wouldn't work. So I moved on to checking the other items under the "If you're still having trouble" part. What finally worked for me is clearing the cache and data from Download Manager, Google Play Services, and Google Play Store. I also uninstalled the updates on Google Play Store, then reinstalled Cytus. I also made sure I had a stable WiFi connection and enough space. I'm not sure which one of these did the trick, but it's probably better to try all of them just to be sure. You don't lose anything anyway if you clear cache from an app.
I paid for the full version of the game over on my old phone and I didn't have to do the restore purchases thing. One thing though, is that I lost all my progress on the game, even if I was already connected to Play Games. But maybe that's because I haven't set up my transfer things and whatnot.
Side note: This also works for other games from the Play Store that won't load. This worked for my Lanota and Tone Sphere that previously had the same problem.
Side note 2: Don't trust pirated APKs or free APK downloads of Cytus on the internet. I tried two APKs from two different sites and none of them worked.
Anyway, I hope this helps someone out!