Every added dimension of complexity adds to strategic options. Not only is there strategy involved in the process of selecting research paths, but in the tech trading associated with it and in the synergy of the tech process with many other elements. Without tech issues, economic issues are less pressing and it dominoes from there. So having a tech research process, as in Civ IV as opposed to Colonization, increases strategic complexity. If having tech is more strategic than not having tech, does that mean having more Techs is more strategically involving than having fewer? Generally, however, there is a diminishing return, when adding each additional tech adds less strategic involvement while adding the same amount of...focus diffusion. Adding stuff to the game that has to be accounted for and micromanaged and dealt with and learned diffuses player focus. Some things increase "strategy" a lot per cost of diffusion, while others give relatively poor bang for buck. Tech, like I said is an arithmetic progression superimposed on a logarithmic one. I suspect that as with the reseach claimed to have determiened that 7 religions is optimal, research also determined that 50 to 100 techs is optimal. More importantly, there are only so many things for techs to DO. When whole new spheres are added, such as Civics, Religion, and Corporations these increase the things that tech can enable and improve, and thus increase the optimal LENGTH of the tech tree. Another issue is the breadth. How many approximate rows are there usually, how many techs researchable at any time? Maybe 4 to 10? Has research been done on this? I suspect so. Many things are designed around that sort of range. I believe it may be related to human short term memory having 5 to 9 chunks available. All kinds of menus are designed around this. Anything outside that range too much is more than we can hold in our mind all at once, so we have to take it in bites like we would if we had to scroll down to see additional rows of techs.