https://mods.factorio.com/mod/ArmouredBiters
This mod adds a new type of enemy to the game called Snappers (which don't replace regular biters), they're a bit slower but have more health and resistance than regular biters. Unlike regular biters, snappers have laser resistance to make building late game defences a bit more interesting. They spawn at the same pollution levels as regular biters at regular biter nests, for example if the biter nest can spawn a medium biter it can also spawn a medium snapper.
Note that the option to enable armoured biter nest works best when creating a new world as they wont spawn in regular biter nests with the option enabled.
YouTube video showing the biters in action: https://www.youtube.com/watch?v=VqCXohS9RWw
- Five new enemies: Small - Medium - Large - Behemoth - Leviathan (not pictured)
- New nest for the biters, disabled by default
- Settings to tweak spawn-rate, health and resistances
- Both normal and high sprite detail settings (the pngs are also optimized)
- Settings to change the snappers colour
Veden - Was instrumental to making this mod, helped a ton
Linver - Created the settings to change snapper stats
MFerrari - Created custom spawner logic and leviathan unit