This is the formula for research cost for v1.29f. I have attached an image of the formula as it is easier to visualize that way than in plain text. Also it is now simplified even more for your pleasure . Research Cost = - Research done so far I'll also write it out for those who cannot view images. Research Cost = [MM * [10*COST * (1 - N/[CL*1.75])]/(CF * 10)] - Research done so far Research Cost and research done so far are in gold. Square brackets indicate truncation /rounddown MM = map modifier(tech rate on world sizes tab in the editor) Tiny 160 Small 200 Standard 240 Large 320 Huge 400 CF = AI cost factor(as on the difficulty tab in the editor) For the purposes of the research cost formula, CF has a maximum value of 10. Chieftain 10 Warlord 10 Regent 10 Monarch 9 Emperor 8 Deity 6 COST = technology cost as on the civilization advances tab in the editor. N = number of civs on the diplomacy screen that have discovered the tech. CL = number of civs left in the game There is only one part of the formula that varies during the game: (1 - N/[CL*1.75]). There are two ways in which you can increase it to lower tech cost: 1. Increase N by exploring and buying comms to add civs to your diplomacy screen. 2. Decrease CL by killing civs. NB. This formula is relevant for research cost of the AI civs, not just the human player. If you are interested in the research cost of a specific technology for a specific AI civ, N refers to the number of civs on that specific AI civ's diplomacy screen that have discovered that specific tech. In general, there are two ways in which you can increase AI tech cost: 3. Keep N low by not selling comms to AI civs. 4. Keep CL high by not killing civs. And technically... 5. Keep N low by not getting techs yourself. Obviously points 2. and 4. are contradictory so choose whichever fits your playing style. Personally I choose point 2.