Sure, there is also a story behind 500k installs 🙂 The point is, I was lucky to launch the open alpha in those times when Google was way more friendly to indie developers.
I checked the statistics right now: the open alpha was launched on the 31st of December 2017 and right after it around 100 players per day began downloading it. It was mostly because I posted teaser images and GIFs on Reddit, Twitter, my own devblog and my Facebook community. But then, after 2 weeks, the number of daily installs became 4000. It was insane! 🙂 As now, in the post-playmageddon times, I understand, that the game's got into the "Games like this" list of some big titles.
The negative side was that the game was very rough those days and many users just dropped off. I kept working to improve it, also added a way to send me a bug report together with the extracted game state to let me recreate the situation. Many improvements had to be made before I fully released it.
After the 21st of June 2018, when Google wiped out 90% of the games from "Games like this" list, the game started getting 100 daily installs and continues do it now.
Right now the game has 9000 active users, according to Google Play. Also small streams are generated by AppStore (7 daily installs) and Amazon (10).