You're working backwards which is messing up your calendar. Either your eras are the wrong age, or you have a crazy high number of turns per era. A standard game, at least currently, lasts 300 turns. The calendar would be more like:

Ancient Era 3500BC - 1000BC; 50 year turn, 50 turns

Classical Era 1000BC - 500AD; 30 year turn, 50 turns

Medieval Era 500AD- 1500AD; 20 year turn, 50 turns

Early Modern Era 1500AD - 1850AD; 7 year turn, 50 turns

Industrial Era 1850AD - 1925AD; 2.5 year turn, 50 turns

Contemporary Era 1925AD - 2025AD; 2 year turn, 50 turns

Eulogos wrote:

Ancient Era 3500BC - 1000BC; 50 year turn, 50 turns

Classical Era 1000BC - 500AD; 30 year turn, 50 turns

Medieval Era 500AD- 1500AD; 20 year turn, 50 turns

Early Modern Era 1500AD - 1850AD; 7 year turn, 50 turns

Industrial Era 1850AD - 1925AD; 2.5 year turn, 50 turns

Contemporary Era 1925AD - 2025AD; 2 year turn, 50 turns

I think your timeline seems a bit more historically acurate, but I'd like to fine-tune it, using the double year per Era adjustment.  So, if you notice, not all Eras are the same in turns, the Medival Era is 60 turns, taking 5 away from the Industrial and the Early Modern Era, and the Ancient Era is a shorter 40 turns, where the Neolithic Era is now included with the leftover of 10 turns from the Ancient, and the total is a perfect 300 turns.

Contemporary Era (2 yr/turn) = 1920 - 2020.  (50 turns) - difference of 5 years earlier.

Industrial Era (4 yr/turn) = 1840 - 1920.  (45 turns) - difference of 10 years earlier.

Early Modern Era (8 yr/turn) = 1480 - 1840 (45 turns) - difference of 20 years earlier.

Medieval Era (16 yr/turn) = 520 - 1480 (60 turns) - difference of 20 years later.  (central approximation for your timeline).

Classical Era (32 yr/turn) = 1080 BC - 520 AD (50 turns) - difference of 80 years earlier.

Ancient Era (64 yr/turn) = 3640 BC - 1080 BC (40 turns) - difference of 140 years earlier.

Neolithic Era (128 yr/turn) = 4920 BC - 3640 BC (leftover = 10 turns) - calendar not displayed, until next Era.

Eulogos wrote:
Why double years though? Do you have any reason to consider that accurate?

The approximation works, not exactly, but reasonably close while keeping the years/turn in each Era the same.  The later thought you had about 35 years per turn and subtracting a year off it every 8 turns isn't level per Era.

Eulogos wrote:
My original proposal was intended to keep to 50 turns per era, so that pacing is ball-park correct if the game is balanced well.

Yes, but the game is balanced even better if 10 turns for the Neolithic Era + 40 turns for the Ancient Era, was an average Era in terms of turns.  Also, historically, given the slow progress made in the Medieval time frame, it makes sense that would be longer by 10 turns, coming from the next 2 Eras, (Reason: the Dark ages containing the plague) catching up to the average pace of 50 turns per Era in the Contemporary Era.  So, Its well-balanced within 10 turns for both cases.

Another point, unmentioned after the standard timeline is loosely approximated:  Should there be a dynamic timeline because of the difference of Empires reaching different ages at different times?

Honestly, reading this whole discussion, I'm more and more convinced that we shouldn't be using BC/AD dates based on our timeline at all. Considering all the math that goes into making it feel okay I'm not sure it's worth it. On top of that, we aren't simulating earth's history after all. You can say that the middle ages in our timeline had slower progress (something which historians can of course argue about till we're blue in the face) but there's no reason why our middle ages should be like the middle ages on earth.

So I'm just going to reiterate my proposal of having each turn represent a certain amount of time (maybe still loosely in pace with the time length of our eras, since they're taken from our timeline, but not too much) and having how it's counted be dependent on decisions (at first counting from settlement for example, or then later counting from the founding of a religion). Of course, I'm not a programmer so maybe that's even more fiddly to implement than all the above calculations.

Alice99 wrote:
Honestly, reading this whole discussion, I'm more and more convinced that we shouldn't be using BC/AD dates based on our timeline at all. Considering all the math that goes into making it feel okay I'm not sure it's worth it. On top of that, we aren't simulating earth's history after all.

What if they could simulate Earth's history, loosely, by playtesting 1 Era at a time, while not considering the stacking combinations of the previous Eras to get to that point - would you be in favor of that?

Alice99 wrote:
You can say that the middle ages in our timeline had slower progress (something which historians can of course argue about till we're blue in the face) but there's no reason why our middle ages should be like the middle ages on earth.

So, the boubonic plague, killing off 1/3 of Europe's population (it really was that significant) can be bypassed?  How would the in-game events do this?  The other warring cultures of the Dark Ages can also be bypassed?  And, what of the crusades - How would that in game event hypothetically be handled?  Slower progress from this Era to the next is realistic, not that history should have happened this way.  Also, is 10 turns a reasonable amount of time to rebuild population and replenish resources consumed by producing war units to what it should be, being ready for the next Era statistically?  Remember, in Humankind, war units also take up population too in the calculation.

Alice99 wrote:
So I'm just going to reiterate my proposal of having each turn represent a certain amount of time

I know you said about the math, and the feel, making it so its not worth it so much, but that is how this goal is achieved I believe.  I do like this thought, suggestion of yours above.  But, then, there's the How - Should it be roughly the same number of turns making perfect math per Era or exactly the same turns for Era, making imperfect math, knowing when one is exact the math for the other one isn't?  Maybe, its possible just like there's a Solar vs Lunar calander, there's also different ways of figuring this one out too.  I hope the computer programmers can take this thread input and make some good sense from it, based on their game design finding the math they feel works for their scenarios the best, which I am excited to try when it comes out, even if the math, turns, and the timelines are horrible!

So, the boubonic plague, killing off 1/3 of Europe's population (it really was that significant) can be bypassed?  How would the in-game events do this?  The other warring cultures of the Dark Ages can also be bypassed?  And, what of the crusades - How would that in game event hypothetically be handled?  Slower progress from this Era to the next is realistic, not that history should have happened this way.  Also, is 10 turns a reasonable amount of time to rebuild population and replenish resources consumed by producing war units to what it should be, being ready for the next Era statistically?  Remember, in Humankind, war units also take up population too in the calculation.

Well, those aren't handled. They've said so before but they're not modelling specific historical events at specific times. The most you have is mechanics and events inspired by them but they're not meant to be those specific events. For example, there's a war grievance based on religion. But there's no specific crusades in the game, and nothing says holy wars should happen in the middle ages and not in the classical era or early modern. Same for the bubonic plague. So there's no reason for progress in this era to be slower than the others, beyond if you want to model it being 1000 years long (which goes for the classical era as well anyway). I don't think 10 turns should be how long the era is, but I'd say depending on your situation 10-15 should be good enough time to recover, if the war wasn''t too destructive. Also, of course, you're likely carrying armies over from the previous era anyway, not just buidling them all in the middle ages.

I know you said about the math, and the feel, making it so its not worth it so much, but that is how this goal is achieved I believe.  I do like this thought, suggestion of yours above.  But, then, there's the How - Should it be roughly the same number of turns making perfect math per Era or exactly the same turns for Era, making imperfect math, knowing when one is exact the math for the other one isn't?  Maybe, its possible just like there's a Solar vs Lunar calander, there's also different ways of figuring this one out too.  I hope the computer programmers can take this thread input and make some good sense from it, based on their game design finding the math they feel works for their scenarios the best, which I am excited to try when it comes out, even if the math, turns, and the timelines are horrible!

Take how many turns an average game takes, take how many years you want in the game. Then check how much time an average era takes in the VIP games. And then you can allocate the time to turns to have it roughly be on the same scale as we experienced those eras. And if the game goes a bit shorter, or a bit longer, that won't be a problem because on a fictional timeline there won't be much of a sense of being "behind" or "ahead."

Alice99 wrote:

... check how much time an average era takes in the VIP games...

They don't have access to VIP builds. Also average time depends on a few factors, such as if you happen to be PARAdoxiBLE...