I find it rather amusing and annoying that people think that because the tech tree is already modded, that the stock tech tree is broken. It's a work in progress and judging from the weekly updates I read prior to 0.22, they were tinkering with it almost daily to get what we're seeing now. I still have my mods from 0.21 installed (they don't seem to break anything during startup, so I'm being lazy about clearing them out) but they have no impact on career mode since the parts aren't 'unlocked' in career mode anywhere in the tree. Therefore, I'm still plugging through it as intended. Are there things that I would do differently if I made the tech tree? Sure--I'd probably move the wings and wheels to earlier in the tree to make more use out of them for all skill levels. Though, now that I know how science works better and how to gain it, I started career again fresh and I'm 4 launches in (with only one successful failure--otherwise I'd probably be 3 launches in) with several items in the 5th tier unlocked so I can do flight this time and get science for it. Thus, I can see why flight parts are where they are--experienced players can make use of them early in Kerbin's science, though for a new or inexperienced (or someone, like me, who got too used to MechJeb or the like) it seems impossibly difficult to unlock while it's useful. Which is another thing to keep in mind when discussing the tech tree. Everyone has different expectations of how things 'work' and everyone has different skill levels they're bringing into career mode. Some will be new players, while others will be people who got used to MechJeb or other very useful tools (and they are useful--if used as a tool, not a crutch), and still others are those who can slap a few engines and tanks together and manually fly the rocket to Duna and back with fuel left over. The main thing I think Squad will be looking at with the tech tree is finding the middle ground which will challenge new players (without scaring them off through being too difficult) while still providing interesting challenges to experienced players. Already, I think they've been doing a good job on the latter--there are a number of threads I've read about how having limited parts are making people try combinations they never had before. Just my 2 Kerbits.