Creep for vanilla Factiorio based on Krastorio2 code (ver 1.2.6). All credits go to Krastor, Linver, raiguard and thanks to their patreons.
https://mods.factorio.com/mod/Krastorio2
But with a lot of changes to make game more challenging and balanced.

Creep must be harvested for military technologies progress. In the endgame less creep is required, but no way to completely automate and produce biomass without fighting native fauna. Here comes Rampant mod to help. But can be played without Rampant or without Rampant new enemies (less interesting).

Features (or read it as changes vs Krastorio2 creep):
- creep absorbs much less pollution, but still noticeably more than common tiles,
- creep footprint grows with evolution and has random proximal part formation,
- creep damages buildings (e.g. "turrel creep" requires timely repairing them and/or some smart tactics), can be turned off in mod map options,
- two types of creep: with biomass derivate (core part of creep areas) and one with bio residue derivate,
- bio residue item is collected in small amounts, used as early game fuel, poison/repair capsule recipe component and end-game recipe ingredient in bio lab,
- Krastorio shovel is used for organics amount measurement, not for cheating fast creep gathering,
- creep is collected by special buildings - Creep Miners. Graphics for them was taken from beautiful old Amator Phasma Coal&Steam and Yuoki Industries mods,
- creep miners work not so magically fast as Krastorio shovel does, but do it with some smart logics and use nearby chests for storing gathered bio organics,
- creep can be collected only after purging enemy nests and worms nearby. Creep type-1 is better protected,
- biters are immune to any viruses,
- biters revenge in form of incoming corrosion blasts is expected when using weapons of remote destruction in mid/end-game. Giving natives a chance vs vehicles, capsule launchers and artillery. Player is still a conquistador here, be smart, move your... wagon, use automated building for creep purge and repairing. Revenge feature can be disabled in mod map options and it requires corrosion to be turned on.
- no peaceful game mode is expected. Biomass is heavily used in midgame and later on for military science packs and Rampant Arsenal items. Bio lab allows to noticeably reduce biomass consumption, but some creep excavation is still required.

Mod is tested for compatibility with Rampant, Rampant Arsenal and Rampant Industry. "New Enemies" mode is not conflicting with creep generation.

!!! TURN OFF "Units affected by tiles" option in Rampant !!!

P.S. I didn't vote for real warmonger, and it's a shame, but I can't do much about it - can't leave children with my wife alone.