Thanks. I'm happy you liked it! :D
Yes, right now, the speed and spawn rate improves each time a rhomboid is spawn, so eventually it becomes a hell.
There are some changes I already made to the spawn rate and enemy speed to make the power-up more useful. There's also an improved power-up (just the same as the actual one but when you use the white ball you get a 6 second buff that make your ship dual colored (red becomes yellow, green becomes cyan and blue becomes magenta). This new power-up comes when killing 2-colored rhomboids.
Finally I'm coding something like a boss enemy. These bosses will be the last enemy from each stage, so no more rectangular/rhomboid spawns until the boss is destroyed. It's not working right now, but I'll make it work. :D
I think these things will make the game a bit more interesting (while keeping the simple gameplay)
Ah, and an android release might happen as well, but I'm struggling right now with making the controls fluid enough to be playable