Tech tree now conceals which technologies are behind Locks (and you will have the ability to circumvent that - though not for free). As tech tree progresses, this will open new mechanics to plan your way through if you are looking for speed or safety.
Fun fact: Although there are several hypotheses Smallpox may have co-developed into the severe form between rodents and their best friends - the farming humans about 3000 - 4000 years ago. Luckily in 1977 after a 19-year process, a vaccination campaign eliminated the disease from the whole planet. The cost estimates ~1.3 Billion USD in today's dollars (so about the cost of the GPT5 training) for the eradication of Smallpox, saving ~15 Million people from death every year since.
New Technology tree is overall progressing in difficulty with new Eras unlocked. Rare technologies will introduce Nemeses after Renaissance era. Other ascensions were also re-grouped to make more sense progression-wise. For instance Auto-skills are accessed in an early branch right behind Stonehenge while Hero recipes can be unlocked from a shared cluster rather than being spread across the tree.
Predicaments are illustrated as a time-bomb triggered by new technology and they're exactly that. Who knew that leeching gold ore with cyanide atop the hill might eliminate all fish in the rivers in 2 years.With secrets you have some way to strategize your path through the Tech Tree. With Locks and Tribal villages being randomized each Civilization, you may need to change approach each time to get to the later era faster.
