This is a great idea, I've been looking for a combination of mods and tweaks that does what you're trying to do, but haven't really found anything yet (early days in 0.22 still) One thing that's been a hallmark of real life spaceprograms is that the designs they came up with were determined by the previous rocketry work that was done by that country, to save time, money and effort. So they might make first stages based on ICBMs, and slap a second stage on top based on an smaller rocket design, to end up with their orbital launcher. In KSP however, you're always free to use whatever parts you have available in whatever combination. While we can't change that, we might use the tech tree to encourage similar behaviour. One idea might be to have many parallel choices in the tech tree, where a particular engine development leads to followup engines that are more capable. Instead of unlocking all tier one rocket engines, you pick a family and base your rocket designs on the path you've chosen. This might require the techtree to assume you have some modpacks installed, to provide more choice. In this way, you'd end up with a techtree with many more, smaller nodes. Instead of a generic 'advanced rocketry' node, you might even have nodes that are just 'Mainsail Engine Development' , and yield just that part. This would give players a choice, to either develop a big powerful engine, or save the resources and cluster some smaller engines, even though that provides lesser performance. Another realism aspect would be that in real life, you can't just build a bunch of solid fuel rockets, do ~science~ and then start flying heavy liquid fueled boosters. You need experience in a technology before it can be developed further. Would it be possible to have the tech tree use multiple resources to unlock nodes? Could we, for example, have flights with tier 1 LF engines yield 'Engineering Experience - Liquid Engines' , which is required to unlock 2.5m liquid engines, and similarly for other categories of parts? Additionally, you might include credits as a required resource, for those that have the mission controller mod. These suggestions entail some more thorough reworking of the tech tree though, and I'm not sure how expansive you want to make this effort.