Developer Comments:
In the last update I made a few changes to the skills and how they work. After testing I realized that those changes didn't fix the problem. I didn't even realize what the problem was, I just knew in my gut that something was wrong. I realize now that the skills weren't offering any strategic choice to the player. It was either apply skill points towards towers that you will use, or apply skill points towards just increasing all towers damage. Either way it led to the very boring choice of: "should I increase all tower damage by 10% or just this towers damage by 10%?"
I have a few ideas for how I can make spending willpower a more strategic choice. The first idea is to tie certain skills together so you can only apply points into one or the other at any given time (example; you can only increase water armor tear or slow effect, not both at the same time). I like this idea because the player would have to choose what skill they value more for any given scenario. This idea could be expanded to some sort of "skill tree" where applying points into one skill lets you apply points into a chain of other skills, but blocks the ability to apply points into another chain. This idea could also be expanded to limit/allow skills based on the number of skill points applied, not just if points are applied (10 skill points into this skill unlocks that skill, but 15 points into this skill disables that skill). This idea gives the player a lot of choice, but would be the hard to implement.
Another idea would be to limit how frequently the player can reset their applied points. Right now it's free and unlimited. So the player can adjust their choice on a whim. If willpower was more permanent, players would think harder about what they actually want to spend it on. I would probably implement some kind of currency that is awarded naturally from playing, and then you spend that currency to reset points (cost would increase the more points being reset).
My third idea would be to increase the amount of willpower needed to increase each skills level based on the level, maybe it could cost 1 more than the current skill level (level 1 costs 1, 2 costs 2, 3 costs 3, etc.) This alone would not be enough to promote strategic choice. It would need to be paired with a different bonus for unspent willpower, perhaps +2 starting essence or +1% tower damage. This gives the player the choice between not spending their willpower for a small boost or spending their willpower for a large boost. The cost increase would add an interesting dynamic where more willpower into a single skill means less efficient use of willpower, but more focused effectiveness for an individual tower. This is my least favorite idea of all the ideas, but it would be the easiest to implement.
Perhaps none of these idea or a combination of all 3 would be best. I am still thinking about it and what will work best for the kind of game I'm trying to make. Feedback and suggestions are welcome. Sorry for the delay.