Here's one way to do it: It requires that you have built a market. Upon killing a human unit, there is a certain chance of a unit spawning inside a market "Being garrisoned". These can be considered, "Slave Points". Slave points are a resource, and they are used to do pay for specialized units that focus on a specific aspect of resource gathering or can be sold for a stable amount of metal. With slave points you can create slaves. Slaves are units that train incredibly quickly and do very well in a certain aspect of the economy (Mining, farming, etc.). Their downside is that they cannot fight, are very weak, and have an upkeep cost. To support one slave unit, it costs 1 food and 1 wood per second while it is alive. There are various slaves you can train: Mining Slave: Costs 1 slave point and 100 of metal and stone. Mines both much faster. Cutting Slave: Costs 1 slave point and 100 wood. Chops wood much faster. Farming Slave: Costs 1 slave point and 100 food. Harvests from farms much faster. Or you can sell your slave points. 1 slave point could equal 100 metal. The benefit of slaves is that you can boost your economy much quicker, which could help someone who is on the defensive, as long as they can efficiently kill enemy units. At the same time, slaves can substitute citizen soldiers in the labour intensive resources such as wood and mining, which means you have more army to command. The negatives is that once various resources are gone, their use is done and you have to kill them.