Yes, but you can't use the tech and civic tree for that. A tech is only unlocked by another tech. A civic is only unlocked by another civic. You can't have a tech unlocking a civic. You may have a tech or civic unlocking projects, but that's useless for the mod as then the project is available in any city without any way to control it. So we must code a new mechanism, preferably one transparent for the AI and not requiring any custom action (like clicking on an item of a new tree unrelated to the base game, without being able to sent the info over the network for MP) So yes, I can reuse the civic tree, but only by copying it and make from it a locked display of an Application tree. It would be perhaps easier to rework the tech tree item to show more data (larger items holding more icons, larger tooltips) yes. Application are their own entities in every proposed design, can you rephrase ? I understand that it may be too complex, and that UI feedback would be important, as usual, but my design allow automatic progression (good for AI and new players) while allowing more experimented players to speed up the items (tech or app) they want to get first (you still have choices) Well, it's planned that way since a long time (more than one year !), and it costed me a few weeks of coding to integrate it to the tech tree, I won't change it now that's the only thing left is to fill the data. Speaking only of the tech tree here, not worked on the app tree yet. I don't think it's an issue, we can make sheets if it helps for development, then think about how to integrate it in the UI. But I don't understand why having hundred of source for research points is an issue for the representation, it would be the exact same problem with one or a thousand of source for points, the "cost" property itself won't change, the prerequisite techs/apps won't change, so the tree and item placement would be the same anyway. I don't thing that you should be able to lock a research if there is a need or another source of points for it (see the previous mention about the AI), that why I propose the other way, ie projects accelerating Apps research, but not researching Apps on projects only. That was my first thought, but too many replacements, can you visualize the list of builder units required ? And the code to select which ones are available in a city ? And that builder could be used on any city plot after being build, no way to lock it to a city area. Units and Buildings are already locked/unlocked at the city level by the fake buildings mechanism coded in the mod, it's a new column in the DB (one in the Buildings table, one in the Equipment table) and 2 lines of code to implement a prerequisite Application.