Many thanks for taking the time to share your insightful suggestions with us! The difficulty curve of the game really needs some more time to be polished. When it comes to the highscore, the original intention of this game is to show that when a person is affected by some negative thoughts, he strives to remain optimistic and sunny. Therefore, keeping the sunshine at the moment is the most important. But as a game, high score maybe a good choise, I will add one later on. Thanks again for your advice!
Ah, that makes sense. A score might have felt too game-y for what you were going for :)
I had another thought, maybe instead of the negative energy zipping past it should stay on the screen getting larger until it pops? It would give a bit more contrast between the negative thoughts that you dwell on and the happy moments that you sometimes fail to appreciate.