I'm using anti biter virus and the evolution does not decrease. Instead it decreases only after I use anti creep virus. Krastorio 2 from start of game.

Factorio 0.18.24
Krastorio2 0.9.17
Other Mods:
ArmouredBiters 0.18.2
AutoDeconstruct 0.1.18
Automatic_Train_Painter 0.3.12
Bottleneck 0.11.3
Clockwork 0.18.5
Dectorio 0.10.7
DiscoScience 1.0.2
EvoGUI 0.4.501
FARL 4.0.1
FNEI 0.3.2
FluidMustFlow 1.2.8
LogisticTrainNetwork 1.13.4
MaxRateCalculator 3.2.35
OpteraLib 0.2.1
Rampant 0.18.11
Squeak Through 1.8.0
Todo-List 18.0.1
VehicleSnap 1.18.2
alien-biomes 0.5.3
alien-biomes-hr-terrain 0.5.1
blueprint_flip_and_turn 18.3.7
bullet-trails 0.5.1
even-distribution 0.3.18
rso-mod 6.0.9
textplates 0.5.2

Hi Pariwak, thank u for ur bug report.

Tested in this moment with the anti biter virus:

If u have use EvoGUI to check the evolution reduction, mod have a strange way to update their conunters, so are not affidable when other mods modify their values.

Thank you for the thorough reply, Linver.

I did some tests using /evolution. I don't know anything about modding so my test cases are probably not that logical. I also deleted then reinstalled Krastorio2 before these tests, even though I think Factorio does integrity checks when loading mods.

First, on a new map I used creative mod to set the evolution factor and got the same result as you. But then I tried in my map it behaves differently. I disabled Rampant and EvoGUI before this test.

I re-enabled Rampant and tried again on a new map without setting the evolution factor and the capsules still work as intended.

Last, I tried again on my map with Rampant enabled and creative mod disabled. I loaded the same save file between tests. I was annotating the screenshots before doing the creep test so there was a bit of delay after loading for the creep test causing the evolution factor to start from different values between the tests (0.4789 vs 0.5175) even though I loaded the same save file for both.

I don't know what is going on. I am even triple checking what is in my hand before throwing the capsule.

Thank u again for ur detail report. I will investigate on this (bug???), seems like a mod incomaptibility to me.

I also noticed that anti-creep lowered evolution, though the tooltip doesn't indicate that it will do this. My evolution was ~97% and it dropped below 90%. Numbers are rough guesstimates. I am playing w/ Rampant, and have not tried the anti-biter capsule.

@Pariwak - In your testing, you didn't keep the evolution approximately the same. Each range of test should have the other combinations tested, or the outliers tossed out--the 0.014-0.019 and the 1.0 test. I say this because the base math, when it incrementally adds time, pollution, and spawner kills, it multiplies the each delta by 1 - evolution_factor, making evolution slow down the higher evolution grows. Whether or not this is a factor in what you are seeing, I couldn't say.

If you want to observe the raw numbers when testing, you can run this:

/command e=game.forces.enemy; game.print (string.format ("ef=%0.4f, et=%0.4f, ep=%0.4f, es=%0.4f", e.evolution_factor, e.evolution_factor_by_time, e.evolution_factor_by_pollution, e.evolution_factor_by_killing_spawners))

Thanks for the suggestions Murdersquish. I made a new map and set the time and destroy factors to 0 so the evolution does not naturally increase. The behaviour is the same as before, both capsule types multiply evolution by 0.66. I do not see how the rate of evolution would affect my original test results in a significant way. If I understand correctly, you are saying that the rate of change decreases for higher evolution values. My objective was only to determine if the biter virus decreased evolution at all. My tests showed that the biter virus did decrease evolution by some amount in a new map with all my mods enabled, which is the intended behaviour. However, in my problematic save, the biter virus does not affect evolution at all.

I did some more testing today using the command you shared and some ideas I had.

I found an old save file of my map from before installing Rampant. I tested the biter virus and found it worked as intended on that map. Then I tested on a newer save file that added Rampant. The biter virus still worked.

I did another test where I made a new map with all my mods enabled, then disabled Rampant and reloaded the map. Doing this made the enemies despawn and the biter virus no longer decreased evolution. However, once I walked enough for the game to spawn more enemies, the biter virus worked again.

I tried this same method on my problematic map. I disabled Rampant then loaded the save, causing all enemies in visible chunks to disappear. Then I walked far enough to spawn more enemies. The biter virus still did not work.

I went back to the earlier save file that had Rampant but still worked with biter virus. This time I threw several capsules, measuring evolution after each throw. If a capsule made enemies disappear, then evolution decreased. However, some enemies were "immune" to the virus and did not despawn. If I threw a capsule and did not see any enemies despawn, that's when evolution did not decrease. I walked around a bit to find new nests and threw another capsule. Sometimes, the enemies were immune and sometimes not, and likewise sometimes the evolution decreased. When I try this procedure on my latest save, all enemies seem to be immune and the biter virus has no effect other than the poison.

This is probably all obvious information since the biter virus is coded to make enemies disappear and decrease evolution, so if one thing does not happen then neither would the other. I think I am okay with only using creep virus to keep evolution in check. It's arguably easier to make than biter virus.