I have played this for 8 almost 9 years
The "Tzars" are the Arabians, The Asians, and The Europeans. Each has a uniqueness to it, for example their wizards and priests do different things/spells. The game basically runs like this... very similar to most RPGs...
You start out, you have a castle and some peasants, with some nearby resources. The resources in the game are Gold, Stone, Wood, and Food. In my opinion, gold and stone are the hardest to get, as their mines run out rather quickly, forcing even the most hardcore turtles and base builders to expand, because your base is mostly secondary, it is all units really. Trees also because they don't grow back and you might not start by a lot. Food is unlimited, where it be from irrigation fields (infinite), fish (finite), or cows (Milk infinite, meat... well you kill them so Finite). You have a wide variety of buildings to build, things to "research/upgrade", and units to train.
The population limit is 200 max but considering every unit costs 1 each, that is plenty big. The game includes a lot of myth from all 3 cultures, there are Djinns, Dragons, Golems, Vampire bats, skeletons, ghosts, etc. The ultimate goal of the game... destroy your foes, sounds familiar doesn't it?
By my description this may seem like every other rts, but I own a lot, of every genre, about 50 total I would say. But, you must play this game to truly experience the brilliance, and skill put into it.
Besides, it has insanely low requirements.