Classical Era (Starting) Units:

Every civ has access to the Classical Era units from the beginning of the game. Until you research more technologies, these units are what you have access to.

Land:

Infantry:

Spearmen: Formation infantry using simple polearms, often in conjunction with shields. Spears (straight pieces of wood with sharpened metal or stone points) give spearmen a reach that allows them to deal with conventional infantry or cavalry safely, at a cost to both their maneuverability--and the overall damage they actually did to enemy forces. Spears are incredibly cheap in comparison to any other weapon, making it easy to outfit large numbers of men with spears. Spearmen cost 1 military manpower per spearman.

Swordsman: Specialized infantry using one-handed sharpened blades, usually short swords forged from iron. These early swordsmen are highly effective at combatting unarmoured troops, but can't be outfitted as easily as the cheaper spearmen (due to the cost of materials and skills necessary to forge a sword). Swordmen cost 1 military manpower per swordman.

Composite Bowman: Archers who use sophisticated bows crafted from overlapping strips of wood or bone. The construction of composite bows allows them to have more power, while still having the same size and draw length of a conventional bow. Composite Bowmen cost 1 military manpower per bowman.

Cavalry:

Horseman: Men who fight from the backs of tamed horses, using either spears of short swords. The advantage of fighting from atop a heavy, swift animal allows horsemen to take down large numbers of infantry even with inferior numbers. Horsemen cost 2 military manpower per horseman, unless the civ controls a source of horses (or is allied to someone who does), in which case the cost is 1 military manpower per.

Skirmisher: Usually employed by nomadic tribes, skirmishers are horse-mounted bowmen. Due to their speed and maneuverability, skirmishers are incredibly formidable, but the training and accuracy necessary to shoot from horseback makes this kind of horseman prevalent only in militaries experienced in both horseriding and archery (if your civ attempts to use skirmishers out of character, do not expect them to be effective). Skirmishers cost 2 military manpower per horseman, unless the civ controls a source of horses (or is allied to someone who does), in which case the cost is 1 military manpower per.

War Elephant: Elephants trained for combat, usually ridden by multiple riders. Despite their apparent strength, war elephants are not epmloyed to cause major damage to troops; rather, they serve to scare troops, and can charge their way through the front lines to allow cheaper infantry to do the real damage. Regardless, a few elephants can disrupt even a well trained force. War Elephants cost 10 military manpower per elephant, unless the civ controls a source of elephants (or is allied to someone who does), in which case the cost is 5 military manpower per.

Siege Weaponry:

Catapult: A weapon constructed from heavy timbers, which uses the tension in twisted ropes to fire large projectiles (often rocks, which could even be set ablaze to cause additional damage) at high velocities over significant distances. Catapults can be wheeled to battle, but are often assembled on site as well. Due to their incredible vulnerability and slow speed, catapults are usually only applied when sieging a city or fort with significant defenses (such as walls). Catapults cost 15 military manpower per catapult, unless the civ controls a source of iron (or is allied to someone who does), in which case the cost is 10 military manpower per.

Naval:

Trireme: A small, agile naval vessel of the polyreme family. Polyremes are powered by rows of oars, allowing them to quickly gain speed. Triremes are outfitted with a sharp ramming 'beak', and do most of their damage by directly colliding with other ships. Triremes cost 10 naval power per ship if they are the most advanced naval vessel you own in the melee class.

Dromon: A small sailing vessel also equipped with oars, the dromon is distinct from the trireme due to its use of the flamethrower-esque greek fire to attack ships from range. Unlike triremes, dromons don't risk themselves significantly when attacking, but require much more refined tactics. Dromons cost 10 naval power per ship if they are the most advanced naval vessel you own in the ranged class.

Medieval Era Units:

These units will be unlocked in the current era as civs research relevant technologies.

Land:

Infantry:

Spearmen: Pikemen are similar to spearmen, though their heavier armour and longer, heavier weapons give them an even greater advantage over sword-users and cavalry. Due to their weight, pikes are wielded two-handed, removing the shield advantage held by spearmen or swordsmen. Pikemen cost 1 military manpower per pikeman. Pikemen are available after researching Steel.

Longswordsman: Swordsmen carrying the longer yet still light longsword. Longswords, considered the most versatile weapon of their time, can be wielded one or two-handed, and have a power that can cleave conventional armour. Longswordsmen are effective against any infantry of the time, though they fare poorly when attacking pikemen head-on, due to their inferior reach. Longswordmen cost 1 military manpower per longswordman. Longswordsmen are available after researching Steel.

Crossbowman: Archers who use a mechanical self-drawing crossbow rather than a coventional draw bow. Crossbows are slower than compound bows, but require less strength and training, and have higher accuracy, allowing for larger numbers of archers to be trained than was possible with compound bows. Crossbowmen were the bane of chariots, dooming chariots to obsolescence. Crossbowmen cost 1 military manpower per bowman. Crossbowmen are available after researching Machinery.

Cavalry:

Knight: Armoured men who fight from the backs of armoured horses, often using long powerful weapons such as the lance. Knights are the heavy calvalry of their time, and are incredibly effective on the battlefield, but are also in short supply due to the cost of the necessary equipment restricting the career to those of noble birth. Knights cost 2 military manpower per knight, unless the civ controls a source of horses (or is allied to someone who does), in which case the cost is 1 military manpower per. Knights are available after researching Chivalry.

Heavy Skirmisher: A type of horseman similar to the skirmisher in function. Unlike the conventional skirmisher, heavy skirmishers made use of push lever technology to wield all-metal crossbows from horseback, making the mounted bowman more accessible to peoples with less experienced riders or archers. Heavy Skirmishers cost 2 military manpower per horseman, unless the civ controls a source of horses (or is allied to someone who does), in which case the cost is 1 military manpower per. Heavy Skirmishers are available after researching Physics.

Elephant Skirmisher: The advent of pikes and more advanced warfare made elephants less valuable as melee behemoths and more useful as platforms that carried ranged attackers. The Elephant Skirmisher, while slow, provides effective cover and foundation for composite bowman and crossbowman fire. The archers sit in towers and the elephants are defended by coats of chainmail. Elephant Skirmishers cost 10 military manpower per elephant, unless the civ controls a source of elephants (or is allied to someone who does), in which case the cost is 5 military manpower per. Elephant Skirmishers are available after researching Physics.

Siege Weaponry:

Trebuchet: A siege weapon with cosmetic similarities to the catapult, it is unlike the catapult in that a trebuchet uses a free-swinging arm and gravity to launch its projectiles with a sling, allowing it to fire much heavier missles over longer distances. Also unlike a catapult, the Terbuchet must be built on site or anchored to the ground, making it even more vulnerable and cumbersome than the catapult. Despite this fact, the trebuchet had unparalleled power as a siege weapon for attacking cities, castles, and keeps. Trebuchets cost 15 military manpower per trebuchet, unless the civ controls a source of iron (or is allied to someone who does), in which case the cost is 10 military manpower per. Trebuchets are available after researching Physics.

Naval:

Caravel: A small sailing vessel primarily employed for exploration. Their light nature and distinct hull shape gave them navigational advantages in dangerous waters. Unlike the more coastal, combat-worthy vessels of their time, the caravel was slow and weak, though it is still substantially more useful in combat than a Trireme. Caravels cost 10 naval power per ship if they are the most advanced naval vessel you own in the melee class. Caravels are available after researching Compass.

Galleas: A variant of the traditional galley modernized to carry heavy armaments. Unlike the caravel, the galleas is designed to be a warship, making it the most effective choice for naval combat in this era, though its combat advantages make it unable to safely traverse deep waters. Galleases maintain the speed of classical era ships, while boasting powerful ranged weapons in addition to simple ramming. Galleases cost 10 naval power per ship if they are the most advanced naval vessel you own in the ranged class. Galleases are available after researching Guilds.

These are the standard units you have access to. Reskins should be based off of these. Unique Units should replace one of these (as in fill a similar role) but should be substantially different. For example, an armored elephant would be a UU.