Map Size: Small
Map Terrain: Temperate
Recommended Side: Either
El Dorado is the strangest Westwood made map that you will come across in Red Alert 2. It is unique in that unlike every other map you start right next to your opponent rather that furthest away from them. The only catch is that there is a mountain that blocks travel directly between the two bases. El Dorado is divided into three sections, each is connected by two bridges. (I will refer to them as top, middle, and bottom) The two starting points are on the top, the middle sections contain two tech airports, near the access points to the bases and a repair outpost in the middle of the section/island. Also, in the middle is access to cliffs that run to both sides of the section. On the bottom there are two oil derricks and a large amount of ore.
There is a total of two oil derricks, two tech airports, and one repair outpost. On the top island there are no tech buildings. On the middle island there are two tech airports(one near each starting point section) and a repair outpost in the middle of the island. And on the bottom island there are two oil derricks(one on each side of the island-left/right, like the tech airports).
Although this is a smaller map I believe that both soviet and allies have advantages on this map so I would recommend either one. However, I do think that the allies have a slight advantage for this reason, as mentioned above in the middle island there is an cliff that runs almost the whole length of the island and if you can control that cliff and put deployed g.i.'s there any unit that tries to go past that section is cut off or will be severely damaged and easily destroyed. However, the soviet strength early one is still formidable if used correctly.
America (recommended) The american side is still one of the most lethal on this map; paratroopers are excellent when dropped in an unprotected area or on a cliff side raining down bullets of death on unsuspecting units and structures, but be sure that you watch out for defensive emplacements, dogs, snipers, or desolators. Often times against a soviet player or allied early in the game they will wont scout their whole area around their base so, paradrop on the edge of their base and then when the land move them into their base, so it is more of a surprise attack. Korea (recommended) The Black Eagle is a formidable weapon on this map for several reasons, first the distance between bases is very short, which means more sorties in less time, also the route for opposing units to take to reach your base is much longer and filled with obstacles(trees, cliffs, et cetera) which again means that you have time for more sorties and that means that you can decimate an army in a short period of time. Germany (not recommended) Nothing takes the wind out of an army like the Tank Destroyer(TD). Perfect for stopping a mass tank invasion or making the initial thrust into the enemies base. However, be sure to keep prisms or mirages near in case of an infantry rush. Also, after you have destroyed his army or economy get the TD out of there and send in your prisms or grizzlies to finish off the base, for TD's are just as weak against structures as they are against infantry. So use this country with caution. Great Britain (not recommended): I would only recommend using Great Britain against Iraq or America on this map. The British sniper is excellent at picking off stray engineers and other infantry but they are easily overwhelmed and vulnerable to air attacks, so be sure to keep anti-air units around them. Another tactic for the sniper is to hide him, behind a tree on a cliff near a forest, and have him pick off the stray infantry, and your opponent will have a difficult time trying to find the source of his problem. France (not recommended): The Grand Cannon has great defensive strength on this map, because the only access to the different sections is by bridges and then the units have to go in two at a time which provides your cannons with ample time to destroy the invading army. However, having said that I would not recommend using France unless you quickly take territory outside your initial base, because if you don't you will eventually run out of funds and the your opponent can build enough units to compensate for your cannons.
Russia (recommended) As usual Russia is of the best, if not the best soviet country to use and that goes for this map as well. The Tesla Tank gives excellent defense against the paradrop(America) and other countries that take advantage of infantry. Iraq (recommended): The Iraqi desolator is highly effective on this map, use him at choke points or to guard against paratroopers. Just be sure to have a flack track near by incase of an air assault. Libya (not recommended): I would only recommend using Libya against another soviet opponent the soviets lack a quick strike air unit so it doesn't matter if your opponent knows that it is coming there is little they can do about it, except sacrifice units to protect their base. I would use the Demo Truck to weaken large areas of enemy units, then launch your attack. I would not recommend using Libya against an Allied player, because they have harriers and rocketeers, which are capable of destroying the Demo truck away from their base and even in your base which will cause much suffering on your behalf. Cuba: (not recommended): As usual I would avoid using the terrorist because it is pathetically weak and often times causes you more trouble than your opponent, so don't give them another option of attack and don't use Cuba.
There is only a limited amount of ore on your initial starting point to get more you must expand and secure your territory quickly, here is a run down of the ore locations: Top island there is a moderate amount of ore near each starting point, nothing else. Middle Island there is one gem cache near each tech airport, one for each player. Bottom island there are two oil derricks and a very copious amount of ore. Try to secure the bottom island and build a huge mining operation, if you can secure it early it can be your ticket to success. However, don't waste too much money trying to secure it if you feel like it is a lost cause, cut your losses and shift your attention to destroying your opponent.
Your first objective is to capture the tech airport nearest you, it will help greatly later on. Then try to secure the cliff on the middle island with units and then protect them with ifv/flack tracks. The put long range units on the cliff and harass everything that comes through there. Next send engineers to capture the repair outpost and oil derricks, then build two to three refineries on the bottom island(be sure to put sentry guns/pill boxes for anti-paratrooper). After you have the enemy boxed in then begin your attack and attack in all directions if possible - that way the enemy can concentrate his forces to stop your bridge crossing. Usually if your opponent gets boxed in they will more than likely surrender for it would be pointless for them to resist, because eventually they will run out of money.
Note: I realise that there is only one land route into the island. I meant that I would attack from land and air if possible.
Sample Build Order
Powerplant » barracks » refinery » air force command » war factory » refinery