First thing, this is great work.

Is there any way, other than directly editing the config files to make it easier to rank up? 50 kills/10000 damage is kinda low for what I am envisioning. I am looking for more of a ramp up, i.e. first rank is 10, then 25, 50, 125, etc.

Thanks in advance!

There is a flag in test which can be set, Unfortunatly i had been asked the entirely opposite prior. May be tricky to emplement but sure there will be a way. Im in the middle of somthing else but I will look at after

I have had a look at unfortunately the way the rank modifier work's I'm concerned it would effect other peoples existing games.
That being said I do have the build in test mode in the file defines.lua
if you return this with what you want I could have the test mode as an option in startup, or if you can edit your self
heroturrets.defines.turret_initial_one_kills_value = 10
heroturrets.defines.turret_initial_one_damage_value = 10
heroturrets.defines.turret_initial_two_kills_value = 50
heroturrets.defines.turret_initial_two_damage_value = 20
heroturrets.defines.turret_initial_three_kills_value = 100
heroturrets.defines.turret_initial_three_damage_value = 30
heroturrets.defines.turret_initial_four_kills_value = 250
heroturrets.defines.turret_initial_four_damage_value = 40