[Arryn]

Originally posted by Spacepain:
As of present I understand that early game is a giant land grab, mid game is collection of magical resources, and gradual build up of small advantages, and the end game is when you let loose all the stored up magical goodness.

More or less, yes.

In the early phase, you must strike a balance between rapid expansion and conservation of your troops. Expand too slowly and you allow your opponents to grow stronger faster than you do, a losing trend. Expand too fast, and you cannot hang on to your gains once you encounter your enemies. Which is doubly painful if you had to bleed excessively to make the gains.

Once you begin to encroach on opponents (or they to you) you must decide who it is most advantageous to attack, where best to hit them (either to weaken them or to strengthen your own position), and when to do so. It is not always best to pick on the weaker opponents first. Often it's much better to go after the strongest ones before they can become even more dangerous. A good exception is to take out enemies on the verge of extinction anyway, just to deny your opponents the resources from capitals. If two enemies are at war, you have the choice to dogpile on one of them and try to grab the spoils and/or hasten that one's defeat, or you can let them weaken each other all by themselves while you take advantage and go pick on someone else (coming back later and killing both of the now-weaker warring parties).

As you gradually expand your empire by annexing the lands formerly held by other empires, you will also be researching ever more powerful magics, and increasing your magical income, while also building magical items to enhance the capabilities of your casters and army commanders.

The end game is reached when you become the dominant power (ie: no single enemy is capable of posing a serious threat, perhaps not even any two of them) and all that is left is the systematic destruction of each and every remaining challenger. In SP, this is easy as the AIs do not stop fighting each other and suddenly all band together Civ-style to try to stop you. Against humans, anyone who grows too strong is likely to get the attention of all the other players, unless you have already worked out some form of alliance. Which, of course, will only Last until someone stabs you in the back (or you them).