The achievements don't work. Surviving past 20 minutes doesn't do anything (except bring out 3 big dinosaurs that shoot spikes), so there's no congratulations or acknowledgement of beating the stage. Once you get high enough movement speed, you can just walk out of the barrier, which makes it a lot easier to survive. Once, I was out of the barrier long enough to witness all the dinosaurs disappear all at once (except for the 3 big dinosaurs that shoot spikes). Another time, I went so far out with so many dinosaurs on my screen that the game crashed and I got an error message.

The highest level I got was 22.