Risk - Strategy
An aspect of Risk that has made it so popular over the years is its realism. It mimics actual geopolitical maneuverings in the diplomatic world. The strategies in Risk rely on fundamental ideas around human relations and the national use of force.
Balance of Power: The prime strategic consideration in Risk is the idea that if a player at any point holds more than half the armies in the world or the potential to get them, he can swiftly overcome all his opponents. For this reason it behooves weaker players to ban together to keep down, if not necessarily destroy, this power. Thus a player who manages to conquer both North and South America generally will be able to sweep the board of his opponents if he is not attacked immediately by all the other players with all the power at their disposal. He should concentrate on one enemy at a time, if possible. For every enemy eliminated is at least three less armies he must confront every turn.
The weaker players, then, should form informal alliances. "Divide and Conquer" should be the strong player's motto, while the weaker players should be thinking, "United we stand, divided we fall." Of course, the weaker players only ban together until the great power is humbled and a new great power rises up from their ranks. This means that each player must constantly balance his relations with the other players. There are no restrictions in the rules about advising other players and such diplomacy should be an integral part of the game. In fact, getting another player to act in your interest should be a primary objective of every player.
Power Bases: A consolidated continent can be thought of as a power base. Possession of even a small continent can almost double the number of armies per turn. It is then important to protect this base and expand from there. Many players like to gain possession of Australia early in the game. Even though it is small, it is easily defended because it has only one entrance. Its disadvantage is that it is far away from other possible conquests. Asia is seldom completely conquered and held early in the game. It is simply too vast with too many points to defend. Since possession of an entire continent augments a players power, it is important to prevent other players from doing so whenever efficiently possible. This does not mean you should spread your armies in an effort to block every opponent's conquests. However, weakly defended continents that can be easily broken up, generally should be attacked at their weakest point to prevent the opponent from collecting armies from its possession the next turn.
In attacking a power base a player should consider his objectives. Is he trying to break the continent? or does he want to take the entire continent? The definition of the objective will largely be dependent upon the number of armies available for attack. To completely conquer a continent and consolidate it in one turn it is generally necessary to have at least twice the number of troops as the enemy has in the entire continent (plus a few to occupy the conquered hinterlands). A continent may be conquered with equal or even fewer forces, but this usually does not succeed or if it is successful leaves the continent open to reconquest or the machinations of a third player. With fewer forces, a continent may be broken - with a roughly equal force to the local armies at the point of attack. If possible, superior numbers should be used because these can be moved onto the conquered country and inhibit reconquest by the enemy.
Army Placement: Strategic placement of armies is vital. The rules often remind players to move armies to the front. This is good advice, but it is best to know where the front is. It is not necessarily where the enemy's power is built up. In fact, it is often wise to avoid great masses of armies. For example, an enemy built up in Europe has 4 border countries to defend. He might build up heavily in the Ukraine, Iceland and Western Europe, but often Southern Europe will be left weaker. In an attack from Asia it would be best to concentrate forces in Middle East and launch into this weak spot. Even though you might also hold Ural and Afghanistan if you do not hold the rest of Asia it would be best not to place any armies in them even though they directly oppose your immediate object of breaking up Europe. In placing armies the idea of "concentration of force" is paramount. You will be tempted to spread armies all over the place, and sometimes this will be necessary, but generally it is best to concentrate power on one objective at a time.
Offense/Defense: Balancing offense and defense is not always easy. It is a maxim in military circles that a good offense is the best defense. But in Risk, as in the real world this is not always the case. When the battle rages between two players one should put every ounce of power in the offense, but when several players are involved, the political element changes this dynamic. Under these conditions it is best to attack when expansion can be consolidated even in the face of opposition. Meanwhile a player should attempt to leave enough force covering his power base (not necessarily directly on the borders of a continent - for example South America can be defended from North Africa and Central America) to deter an attacker who must also be worried about what the several other players will do to him should he become too weak because he spent too many armies attacking you.
Armies can simultaneously perform both an offensive and defensive roll. For example a player controlling North America might attack from Alaska to Kamchatka and place all of his armies in Kamchatka. The border has been expanded and the bulk of armies still protect the power base of North America. There would be little sense in leaving more than one army behind in Alaska except for "political" reasons. (For example the object of the attack into Asia may simply have been to get a card and the number of other troops rampaging about the continent make certain that Kamchatka will be attacked even with a large number of troops situated there, while the same players might think twice about crossing the Berring Strait if North America plays no immediate part in their grand strategy.)
All these strategies assume perfect conditions and the availability of many armies. In the game of Risk, until the balance of power becomes terribly skewed, there never seems to be enough armies to accomplish your objective. Thus, you often have to rely on luck. Napoleon famously said that he would rather have a lucky general than a good one. Then if you must take risks, take calculated risks. Consider what might be gained by a particular attack or for that matter not attacking at all for a turn. Don't squander your forces in hopeless adventures. Bide your time, collect your cards and attack when the conditions are right. Remember, "suicide missions" are a sign of an undisciplined player. You never know what will happen in the next round of play. Luck, card armies and the actions of other players could suddenly catapult you into a powerful position.