For the values of the coins, my guess is to simplify things. I think the idea was to optimize between having a small number of different coins and a wide range of possible values. You have to remember, this is a medieval time period, which means no fancy minting factories where they can just churn stuff out by the millions. So the fewer different types of coins they have to produce, the less work it takes and the cheaper it becomes to produce the money, meaning more budget for other things, like extra cheesecake at important government meetings. So, they skipped some of the intermediates, like 5 and 25.
As for the shape, it would be nice if that was relevant, but it doesn't have to be. Also, I wouldn't be surprised if it used to be relevant at one time, but if the numeric values have been adjusted over the years to what they are now, probably either due to some revolution (like in the real world with the French Revolution and Metric), or in attempts to combine the monetary systems that each race brought with them into something that all races would find acceptable.
If the amount of coins is kept at a certain level("repair broken coins and replace the ones that leave the city or get lost somehow" I don't see mining new ones here) how come coins are not getting rarer and rarer, since there are more and more people.
My assumption is that the level is actually a ratio of coins per person. So more people equals more coins overall, but same ratio, thus same value.
Now, if we take into account that the population
isn't increasing, the number will actually remain the same. If this went on for many years, people would just take it for granted that there are X coins floating around. If there were a big disaster though, they'd either realize that the total number will have to start adjusting again, or experience inflation.
EDIT: I should clarify something: Yes, more players enter the city every so often, but that doesn't mean it's growing. Just that more of the population consists of us. But until the number of human players summed with the number of NPCs is greater than the population of the town, it's irrelevant. When we reach that point, then it will be growing. But remember, Hydlaa is bigger than it seems. It's not fully implemented. By the time we have that many people, there will be plenty of other towns out there and people will be spawning all over Yliakum.
As for overpopulation, don't forget these are medieval times. That means:
A. People have shorter lifespans
B. Children have much much lower survival rates than now, especially babies
C. Successful births are also going to be less frequent (no modern hospitals and such; most babies will be delivered by the father, a family member, or a midwife)
D. Potentially a more conservative view of getting jiggy with it, possibly fueled by the lack of birth control. This could be countered by the larger families in older times, but that generally only applies to people in the country (Bigger family == more hands to till fields. But in the city, your income won't increase as much from having kids).
Not that overpopulation can't happen in medieval periods. As I understand it, overpopulation was a big factor in making the black plague as nasty as it was. But, that was probably over a thousand years after humans started settling in Europe. Yliakum, on the other hand, is only ~750 year old, if I remember correctly.
For weather, I've wondered this also. I wrote up how I figured it could happen a year or so ago, so I won't repeat it. Search would probably turn it up. I don't know how realistic my version was though, I'm no meteorologist.
