The Tech Tree - Humans

A so-called "Tech Tree" is a requirements map for buildings and units.  Essentially, certain buildings and units need specific types of buildings completed before they become available for build.  Here's a useful picture of the Human tech tree.

As you can see, the above picture only shows the requirements for buildings, and it does not show the requirements for units.  So, I'll list the requirements for units below.

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     Units                  |            Requirements             

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1.  Peasant                 |              Town Hall

2.  Footman                 |               Barracks

3.  Rifleman                |           Barracks, Blacksmith

4.  Knight                  |  Lumber Mill, Blacksmith, Castle 

5.  Spellbreaker            |  Arcane Vault, Arcane Sanctum, Keep

6.  Priest                  |         Keep, Arcane Sanctum

7.  Sorceress               |         Keep, Arcane Sanctum

8.  Dragonhawk Rider        |         Arcane Vault, Keep

9.  Gryphon Rider           |          Lumber Mill, Castle

10. Mortar Team             |      Keep, Blacksmith, Workshop

11. Flying Machine          |      Keep, Blacksmith, Workshop

12. Siege Engine            |          Castle, Blacksmith