hi i love this mod and i love the extra challenge it brings but uh, personally i would like to be able to change the spawn rates, 20's are so rare and i have yet to get anything above a 16 so far and would like to bump them up a bit as the 15s and lower im getting are kinda pushovers for me and im not getting the hell i want. im not expecting the addition but it would be great ^^

To my impression of a reasonable alien (or human) social formation, it gives much more sense the population comes with a pyramid structure: The king/queen comes very few. A few generals (the strongest) commanding the more lieutenants (medium powered), and the swarms (the weakest) form the main force of the alien army.
I wanted to resemble the similar thing in this mod. I have used the golden ratio (0.68) as the asymptotic multiplier in the quantities, so each tier higher is this factor less than its lower.
Therefore, I do not modify that as my "official" release.

BUT if you desire to change the factor in you own customized version, it is POSSIBLE. Decompress the mod ZIP file. Open file prototypes\enemies.lua. Then find the two lines with spawner.result_units. (One for biter-spawner, one for spitter-spawner.) For example, in mod 0.18.1 you can find line 160 & 298.
Line 160 is:

table.insert(biterspawner.result_units, {unit.name, {{1 - 0.1 / math.pow(2, (tier-4)/difficulty), 0.0}, {1.0, 0.4 * math.pow(0.68, tier-4)}} } )

Modify the value 0.68 to some larger values.
Setting to 1 will give different tiers the equal chance.
Setting to >1 will give an "inverted pyramid", high tiers will be more than low tiers.

thank you.