Slitherine

Can someone make a guide, or at least talk me through how to make cooperative multiplayer scenarios?

Simplest way is to simply create a 'normal' single player campaign, ensuring that you set up the teams on the player units to denote which is for which player. Then in the CAMPAIGN.TXT file you need to add COOP below the entry for each mission, e.g:

[myMission]
COOP

[MySecondMission]
COOP

etc

You can in fact have some missions which you don't 'allow' for coop.

Cheers

Pip