Thank you for playing and for the feedback!
1. I might adjust this when/if I add more enemy types. Currently new enemies are introduced on levels 4, 8 and 12. If I introduce them much earlier, the later levels would get boring as there would be nothing new to expect.
2. If you mean the round "mines", you're absolutely right. They have already been redesigned for the next version. They now trigger when they see the player for long enough time and explode sending fragments towards the player. They are still stationary but now they actually pose a threat.
3. There is a shield power-up that lowers the damage taken on hit but there is no way to recover your health. This is a design choice. The game is designed to be an endless high score shooter where the player eventually dies and avoiding damage is the most important thing.
4. That's a good point. I could make the enemies aim a little smarter at higher levels. Currently they only get tougher and shoot more/faster.
5. They are drones in zero gravity, guarding their designated positions. I don't see why floating makes any less sense :)
The reason why most enemies don't move and none of them actively follows the player is that I want the player to always be able to retreat to safety and relax for a while. I also wanted to enable more careful play style where you can sneak behind corners and trust that enemies don't sneak behind your back. This is also why there are no time limits or time score bonuses.