The Rohan Open-World map is a fan-made map which presents the user with a small version of the Land of the Horse-Lords. It includes the most iconics fortresses (Hornburg, Edoras and Isengard) along with a chunk of the Fangorn forest. It is a representation of the wide plains of the Rohirrim on which Isengard and Rohan will battle to claim lordship over it in a manner true to the game's lore.
When you play as Rohan, you have to protect the civilians of Rohan from the invasion of Isengard. They are represented by 6 "battalions" of civilians, which are at the start in Edoras. You can bring them to Helm's Deep, which offers a much better protection than Edoras, but much less recruitment buildings. You can also decide to keep them in Edoras, but I think it is harder to protect them there. You should also defend the Rohan farms and villages which are outside the cities, because they produce almost all the resources you will need. To win the game, you have to destroy the dam of Isengard. For that, you can have the help of the Ents of Fangorn.
When you play as Isengard, you have to destroy the people of Rohan (so kill 3 of the 6 battalions of civilians). At the start, you can only train Warg Riders and wildmen if you explore a little bit. More buildplots will appear progressively after time in your base, but if you want to have more buildplots, you have to destroy the farms and villages of Rohan. When you destroy them, buildplots appear for you at the same places.
The Rohan player begins with most of the map control and control of Edoras. Edoras has many building plots and buildings which grant resources and allow for the recruitments of units (Swordsmen of Meduseld, Axe Warriors, Yeamon, Rohan Pikemen and Rohan Captain) beyond the ones provided by regular recruitment buildings. In addition a camp in the center of the of the map is already under the control of Rohan with a well (for healing), Assembly Point (for defense) and multiple Stud Farm (resources and reduces cavalry cost.
The Rohan player can also take control of Helm's Deep, as long as Theoden is cured. This defensive place can withstand a lot more suffering than Edoras but the buildings plot are much fewer and the there are no resource buildings. It's important to try and keep the outside camp and surrounding farms alive since it gives you the vital resources you need to push back Isengard.
Finally, if he wishes, the Rohan player can gain control of Ents and of an Entmoot. To do this first you must go see the Entmoot at the top of the Map in the forest. There Treebeard will ask you to destroy the Lumber Mills located left of the forest, once this is done you will gain control of the Ents protecting the Entmoot and of the Entmoot.
The Isengard player has access to multiple camps in addition to Isengard from where they start. In Isengard the player starts with 8 buildings: the Orthanc (to recruit heroes and research upgrades), two Lookout Towers (defensive sentries), 2 Lumber Mills (resource gathering) and to Warg Pit (to train Warg Riders, rearch Blood Wargs and Machinery of War), and the Dam (which, if destroyed, causes defeat). As the player researches new spellbook powers (apart from the Tier 1 powers) new building plots will unlock inside of Isengard enabling the player to build more buildings.
At the bottom left side of the map there is also a Wildling camp which the Isengard player can take control of by bringing any allied unit the the spotlight. This will give the player access to two Clan Steadings (to recruit Wulfgar, Wildmen of Dunland and Wildmen Axe Throwers), a Slaughterhouse (for resources), an Outpost (for resources) and two Lookout Towers (for defense). The player of Isengard also has access to a Orc Camp and bit on top of Edoras on the right side of the map. This Orc Camp has access to two Orc Tents (to recruit Grishnákh, Grisknákh's Boys, Orc Pikemen, Orc Archers and research Banner Carrier). Finally, Isengard can also destroy the Rohan Camps in order to gain some more buildplots.
- Think wisely before letting Edoras be destroyed, it may be weaker but it has a considerable bigger amount of building plots, however if you see that your enemy is trying to overpower you with merely units it might be a better idea to fall back behind since attacking Helm's Deep requires siege.
- There is no point in destroying your initial building, this will not grant you new buildplots.