The expansion changes nothing in the basic formula of the game. The graphics are still beautiful. You still gather food, wood, stone and gold to build up your economy.

With those resources you construct buildings such as mills, farms and barracks so you can raise an army of cavalry, infantry and archers to conquer the world.

Technology-wise, your resources can be used to pay for research that advances your civilisation, technologies such as crop rotation (to improve farming), masonry (to strengthen buildings and walls), and blast furnace (for better steel and stronger weapons).

The differences in the Age of Empires civilisations have always been subtle. I estimate them to be about 80 per cent similar.

Mastering Age of Empires means learning how to apply the strengths of the remaining 20 per cent against the weaknesses of the other civilisations.

Less serious students of Age of Empires II will attempt to conquer the world and conclude that Age of Empires II is a battle between 13 identical civilisations.

Serious students will conquer the world (and less serious students), write essays on the strengths and weaknesses of each civilisation and roll their eyes when other students talk about 13 identical civilisations.

There are five new ones - Aztecs, Mayans, Huns, Spanish, and Koreans. Ensemble Studios includes a brief background on each civilisation, summarising their history and showing why each civilisation is included in the game.

My new favourite is the Aztecs. Their Unique Unit Jaguar Warriors specialise in anti-infantry tactics. Other new units include the Hun Tarkens and Korean Turtle ships, the first armoured war ships in history.

The single-player campaigns explore the battles between the Spanish and Aztecs. You will also learn about Atilla the Hun and El Cid and the battles they fought.

Students of warfare may know that the battles of Agincourt, Manzikert and Hastings were cusps in world history. The campaigns in this expansion let you simulate these battles and see how you might have fared in them.

I love the history that I learn from the Age of Empires II series. The backgrounds and simulated battles combine to reinforce learning.

Each civilisation gets at least one of the new technologies included in the expansion. For example, the Chinese get Rocketry, the Huns get Atheism and others get Herbal Medicine.

New game types introduced include King of the Hill and Defend the Wonder. They are a refreshing change from the simple 'kill everyone' games.

Many game-balancing changes have been made. Cavalry was a little too strong so a more powerful pikeman unit, the Halberdier, was added. Weak camels had their movement speed and defence values increased. Horse Archers are faster and more accurate.

I recommend this expansion to serious students of Age of Empires II. If you did not recognise any differences between the first 13 civilisations, though, adding five more is not going to make your vision any clearer.

Graphic: rev17gwz