there are four technologies of each group for each epoch. technologies can be researched by spending tech points. to get tech points, an appropriate number of citizens must be garrisoned in a university and/or an appropriate number of priests must be garrisoned in a temple. technologies are researched through the main interface (no longer through a building) by clicking the technology tree button. when the correct amount of tech points are available, the tech tree button will light up and new technology to research can be chosen. however, when research is no longer used (at the highest epoch specified before starting a game), the garrisoned units will become idle.