Resource and enemy bases spawn rework. Biter attack mechanic changed to work on timers, to make more interesting combat with steady difficulty. A lot of combat, pollution, modules, technologies and recipe changes. Early equipment technologies.
Large total conversion mods.
Armor with equipment slots and upgradable (with tech) reactor/battery/exoskeleton/roboport is available from the start. Original exoskeleton is disabled for player armor. Early construction robots with very small battery.
Mods introducing new content into the game.
Quality modules only work in special building - Disassembler, which can work as quality upcycler. Quality modules guarantee quality upgrade, but have high penalties. More complex items have lower chance to upgrade. Quality modules can't have quality. Quality bonuses are increased.
Small changes concerning balance, gameplay, or graphics.