First of all all the players will decide whether the game will be played cooperatively or competitively. In the cooperative game all players will combine to develop the trading colonies and help each other as much as possible to stave off the depredations of the Four Horsemen of the Apocalypse - either you all beat the Horsemen's score or you all lose!
Competitively you have to beat the horsemen's score still but you have to be the highest scoring player individually. It won't be easy either way!
The game is for 1-4 players and plays in around 120-150 minutes with 4.
The Horsemen cards are turned over at the start of each turn and indicate where the Horsemen and their earthly avatars - Shadows - will be active in that turn. You will not be able to operate yourselves in those areas during that turn. The cards also show how many action points the lead player and everyone else will have available that turn.
Full rules are downloadable on the BGG page for Darien Apocalypse.
There will be Garman rules available for download on the BGG page.
Each player has an array in their own colour and uses this to indicate with action markers which action they are taking and in which order. As the active player in a turn you will have more actions than the others and they must decide when they will use their actions to emulate some of yours - timing is everything!