Yes, it is as VN said.
There are so many factors that add to the difficulty of the game.
Shot range, damage, armor, shot frequency, spawn frequency and count, and more.
The enemies automatically level up after each wave and world.
Until recently, I could very easily play through to the end. Without taking any major losses. Almost boring.
Then I thought to myself, let's just set the armor of the enemies a little higher.
At the same time I added my last ship type. after that the game was no longer manageable.
Still need to tweak a bit.
