Double XP Events

"This weekend you'll find that you're earning DOUBLE XP throughout your Outpost! If you're looking to gain some (or a bunch) of levels, now is your chance to do it fast. Earn more XP as you complete jobs, collect taxes and complete missions."

- Ikki

Overview
Double XP Events are, like their name suggests, promotional events that double all XP earned by players for a limited amount of time. Players can earn XP through completing Missions, collecting goods and taxes from Shops and Housing, or by promoting units. As of the 4.0.1 Patch, there are two types Double XP events: "Double XP Weekends" and "XP Extravaganzas".

The Double XP Weekend was the first and only kind of Double XP Event until the 3.3 Patch, when XP Extravaganza was introduced. Double XP Weekends occurred rarely, giving players only a few days to level up a few levels before the event ended. The Extravaganzas seemed to have replaced the regular Double XP Weekends and include an added 50% discount on the purchasable Super XP Boost.

So far, there have been a lot of Double XP Events:

Double XP Weekends:
 * September 2012
 * November 2012
 * October 2013
 * November 2013
 * December 2013/January 2014

XP Extravaganzas:
 * February 2014
 * March 2014
 * April 2014
 * May 2014
 * June 2014
 * July 2014
 * August 2014
 * September 2014
 * October 2014
 * November 2014
 * December 2014
 * January 2015
 * February 2015
 * March 2015
 * April 2015
 * May 2015

Other Double XP Events:
 * Veteran Sale & 2x XP, June 2013

XP Boost Stacking
When any Double XP event starts, players still have the option to purchase an XP boost for Nanopods. Thus, if a player decides to purchase an XP boost during the event, the boost will be stacked upon the existing event and all earned by the player will be quadrupled (x4). Note: Only one boost can be active at any time.