This mode should be free to activate, once activated, it would freeze all resource productions and make the player lose all occupied oasis and forts. Alot of people have negative crop production for their troops, so this should be frozen also until the player returns from holiday. The players cannot be attacked by anyone else in this mode.
To make sure people don't abuse this function, there might be certain rules regarding the activation period of this mode. Such as once you activate the holiday mode, you cannot exit the mode for minimum of 1 week. During that time you cannot make any changes to your city, you can perhaps log on but cannot issue any command.
Also, before one can start the holiday mode, the player cannot attack another player for maybe 24 hours minimum. This is to prevent hit and run before someone go on holiday.
I have a trip coming up in two months time and might not be able to login for about 3 weeks hence why I want this function.