The purpose of this add-on is to extend each faction with units they don't have in the standard eras; for example, dwarves don't have a mage or healer in the standard eras, now they have in these extended eras. Basically, they are the default Wesnoth armies, but with additions, and a very small number of edits, to keep them balanced.
Also, in this add-on are additional maps for hours of gaming fun.
More information can be found on http://forums.wesnoth.org/viewtopic.php?f=19&t=37358
Ported to 1.14 and 1.16.
1.12 version was also updated and thoroughly debugged before being ported. Available on request. Contact me privately via the Wesnoth BBS.
The 4 included scenarios all use this era's units in scripted battles. One of them is a fully scripted survival pitting the new and original Monster Horde faction vs 8 AI opponents attacking from all sides. In another you take on the role of 3 Orc (extended armies era faction) commanders besieged by 6 AI attackers. The other two scenarios also pit you vs the AI survival style as you play the Monster Horde.
Nine other maps originally included with the era have been split off into their own add-on called BomSite Maps. They work with any era.