rules.js
Each human player in a game will have an associated rules.js script assigned to them. It runs for the duration of the game.
The rules.js script is responsible for applying and monitoring game rules, and providing in-game situation reporting (SitRep) to the human player.
Game Rules
There are three key parts to the game rules as follows:
You should make yourself familiar with all of them, even if you have no intention of modding them.
Situation Reporting (SitRep)
Realtime (or near-realtime) reporting of important events taking place in the game.
For detailed information, see: