So, you want to know more about the Stellaris tech tree? The idea of 'tech trees' is no stranger to space 4X games like Stellaris, but Paradox's vision for the concept is slightly more unusual. Instead of a static, known web of potential technologies like most strategy games, Stellaris adds an element of randomness.
Stellaris' technology interface is split into three sections, one for each of the core disciplines of Engineering, Physics, and Society. You start off with three randomly pulled techs for each area, with built-in biases as to what techs you are shown. Every time you research a tech a new one is chosen at random, again, following certain biases. If you ever discover or unlock something via an event, it will also show up in this interface and stick there until you research it.
This 'card shuffle' façade introduces a touch of the unknown to any individual run - you're never quite sure what techs will unlock in which order, although like a traditionally tree different techs are strung along a path which you'll need to follow towards the end. This means that, despite not being able to control what tech you get at any given point, you can still plan for your end goals.
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Stellaris' 3.0 Dick patch isn't even out yet, and it's already been updated