I was stuck for a while trying to figure out what to do, how to earn points, etc. I thought it was a wave-survival type thing but I had -215 points that would go up and down seemingly randomly.
However, I eventually realized that you move right to gain score. Seems like a lot of people had issue with this too, so maybe just some indicator at the start to move right (just like an arrow on screen at spawn is probably enough).
After that it becomes a nice casual game like doodle jump :)