There are many custom units, like flying elves, sentient plants, dwarves, monsters and undead. You'll have to check out the link above or just play the map to find out!
I just started a game. Looks interesting, could be fun!
http://atwar-game.com/games/?link=0294633772
Name of game: RatWar's Game
Name of map/scenario: XKCD
Date initiated: Oct.17
Turn time (12-48h): 48hr
Starting funds (3-50k): 10k
Max. players: 12
Number of teams: 0
Alliances: 3
Max Turns: 50
Join until: Turn 3
http://atwar-game.com/games/?link=0294633772