They Are Billions Coop !!install!! -

The modding community has extended the game's life, though true multiplayer mods remain elusive due to the engine's hardcoded limitations.

For the hardcore community, the definitive way to play co-op is via the Stormgate mod (formerly known as the "Co-op Mod"). This mod unlocks the beloved Survival/Skirmish mode for multiple players. It allows for a level of freedom the campaign does not: shared resource pools (or split pools depending on settings), independent tech trees, and the ability to utilize the massive roster of units available in the editor. Most serious co-op play happens here, where the "Billions" truly feel like billions. they are billions coop

There is a paradox in TAB co-op: