I think that stronger units is a step in the right direction, but still doesn't allow enough visible growth for the player. Ideally, I want things to look different on the battlefield when I buy upgrades. Like unlocking new units, giving units weapon upgrades that change projectile colors, or equips them with new weapons entirely (guns -> lasers, etc.). The jetpack units could be an upgrade to the ground units to make them move faster too.
I hope you don't mind me giving so much input. I just find the potential in the game exciting!
Viewing post in Trolls vs Robots jam comments
Totally! the visual aspect of the upgrades is super important, because it doesn't feel as good to watch numbers go up as to see an actual change in the units behaviors. I think that changing the guns the units handle could be a good idea, because i could change the gun sprite without animating or changing the units much, like the laser example. In the flying units case maybe i could give them a bigger/ more badass jetpack when they level up, making them faster and deadlier.
Don't mind the input at all, i could be talking about game design all day to be honest haha