I would divide the technologies in the tech tree into several types:
regular - unremarkable technologies
Great discoveries - great discoveries that can radically change the gameplay, example: agriculture, steam engine, animal husbandry
Dangerous technologies - technologies that pose a danger to the player, but if used correctly, the player can benefit from this, example: nuclear weapons, strong artificial intelligence
Change “Great” for “Revolutionary” and “Dangerous” for “Double-Edged.”
After re-reading (that is why this is edited), I think those labels could actually describe the type of discovery, but not actual tree splits.
My suggestion which differs a bit:
Wouldn’t it be more interesting to divide discoveries into scientific fields and then each would have an identificator like shape or color which explicits those classes you said above?
Obviously, by following a branch, we would see how discoveries were dependent on previous discoveries from different fields. However, in order to make trees somewhat simple, only key and high impact discoveries should be included.
Imagine a country researching the dark forest theory and releasing that info hazard to another country in order to win a space race but the second country goes anarcho primitivist accelerationist and invents an artificial general intelligence and uses it to send their planet back to the pre agricultural age except it is still industrial and robots are gods but they don’t tolerate technological progress but a space battle on the orbit releases an emp blast which knocks out the robot overlords and a secret society speed rushes technology but the winner of the alien space war in the orbit sees this progression and decides to colonise the planet and experiment on the suddenly advancing species but in the meanwhile the AI fixes itself and copies itself to the galactic internet, deactivating all the technology on the galaxy, and the species that was being experimented on launches a slave rebellion, someone can write a triology about that