Crew wars share many things in common with battles; however, instead of being between 2 crews, they are between all crews and last 3 days rather than just 24 hours.
These will happen every 3-5 weeks, starting at different times throughout the day/night. All wars follow the same rules as a battle (except that there are 3 rounds of scorecard challenges). The winning side gets a score boost based on percent of total points. They also get their original buy-in back and any Chips left are split between crews and members based on points scored.
Every crew with 3+ active members is automatically entered. Three days before war begins, the previous war’s top 2 scoring crews are selected as team leaders (based on previous war scores). They can then vote on their top team member selections (like on the playground), and after 24 hours, Team Black and Team Blue are selected (ties and lower picks alternated by ranking).
No battles are allowed past this point or during war. There is an automatic entry fee of 25,000 Chips and 10 Casino Points per member after the first 3 (so a crew of 5 would have 50,000 Chips and 20 Casino Points deducted from the crew bank). Any crew that can’t cover is excluded.
Each player gets a scorecard during the war, which you can access by clicking the green flag in the top left of the screen. This provides them with a variety of personal, team and bonus challenges. Each time you complete a personal challenge, your score will be updated if you beat your previous high score at that challenge. You can then unlock bonus challenges by completing each personal challenge once.
The team challenges require a group effort to complete. Each team has the same challenges and they must be completed in order to unlock the next one. There are 5 team challenges per battle, and completing each one gives a boost to the overall team score, with a maximum of 25%.
Unlike in battles, these scorecards reset every 24 hours during the war and you are able to start fresh. Your overall score is the total of each of the 3 days of scorecards.
You can watch the live results of the active war by going to the “BATTLES” tab of the “All Crews” window. You can also see the live stats and per-player scores of the war by going to the “BATTLE” tab of your crew's window.
When you aren't in an active battle or war, the “BATTLE” tab displays a list of past battles and wars. Clicking on these gives you an overview of the outcome of the war with point breakdowns per crew.