L15 plus just gets ridiculous.
I like these kinds of games unfortunately I feel like it could be so much better. It would be nice to get upgrades. A lot of games like this have upgrades. Something like a machine gun or an area of effect explosion would be nice especially for the higher levels.
The planes could use exploding animations and possibly a nerf in HP or make them far less common. Another thing is I saw a lot of shots get wasted on troopers that were already on fire making it annoying when they are stacked making your waste a lot of time double firing on 1 guy. At later levels this means you are pretty much guaranteed to be stuck shooting them on the ground which you can still kill them from there.
You can't kill anything that is clearly in the middle of your turret. Very annoying and I pretty much died to 1 guy since I couldn't kill him in time. :(
Another thing that sucked was as you progressive the troopers at a tendency to spawn pretty close already to the ground. At L20 you are essentially having them spawning in the middle of the screen. Compound that with the fact there is like 20 of them and they are moving 10 times faster than 5 levels ago then you pretty much reach an ending point and are guaranteed to lose momentarily.
It would of been nice to have more enemy types too. Maybe have the planes drop bombs I gotta shoot down or special troopers that shoot or move faster. Add some upgrades to assist in managing them so the game is a more fun experience.