How to install?

Extract the zip file into your Mods folder, start a new game and select the They Be Biters Preset in the map generator.

Is this compatible with other mods?

Some parts will, others won't.
The moat generation is minimal and only affects the generated terrain at the start. The map settings are part of the base game.
The biter and spawner changes affect the vanilla prototypes so change to those will cause conflicts.

Will this work with an existing save?

Somewhat. The moat generation won't but everything else will.

I get desyncs in multiplayer?

Have everyone load into the game before applying any mod settings as this clears all enemy units from the map (don't worry, they come back quickly).

Can I change x?

The in game mod settings has most things you'll want to change.

Recommended mods?

Invulnerable Rails is very, very necessary
Loot Chest is a kickass mod that incentivises taking out biters.