Welcome to the X-Entertainment Advent Calendar Wiki.
Below is an attempt to catalog the Plots, Characters, and Misc. stuff that has happened throughout the years.

While 2002 was little more than a commentary about each piece, and 2003 was some of the same with small bits of dialogue added, 2004 switched from Matt's narration to a purely dialogue driven story. From here main characters were fleshed out and continued to detail a story that bridged each year.
For each season, a new calendar appears for the cast to open each day. The rules are simple: open a box on the appropriate day and no sooner. That and fend off the forces of evil that try to ruin Christmas each year.
Calendars:
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Additional Info:
Character List, Items of Importance, Calendar Gifts, Figure Sources