I'm having an odd experience with the latest JGRPP pack. (I'm posting this here because I don't know if issues with JGRPP that aren't clear bugs are appropriate in the development subforum or not; and also because I don't know how to tell for sure that it's a JGRPP problem.)
This is jgrpp-0.27.1, with the full suite of Japan Set NewGRFs. I'm running with the day length factor set to 5. This game (and all the games I'm sure I've had this problem on) have been custom scenarios with a random sub-arctic map, manual city placement and no industries. (No cities are above the snow line, and none are marked as 'cities', they're all towns technically.)
In short, when I connect a city to my rail network, it quickly begins to shrink. The most visible indicator is my graph of passengers carried per quarter:
File comment: passenger volume showing steep drop
openttd jgrpp city death.png [7.99 KiB]
Not downloaded yet
The last new line was built in January 1984 with a few minimal capacity upgrades in the rest of 1984; I have done nothing but run the clock since then. Nevertheless, for the last two solid years (December 1984 through December 1986), passenger volume has shrunk quarter-over-quarter. I'm now transporting barely more than half
of the passengers I was two years ago.
Looking at the world population, I see that it's at 32,655 as of Jan 1 1987; when I started in 1980 it was 36,398 (and reached a peak somewhere above 37,000 around 1983). The cities I haven't connected have stayed the same; however, the cities I have connected have shown some fairly dramatic drops. The first city I connected, and the largest I've connected yet, started with a population of 2,815 in 1980; seven years later it's fallen to 1,857 (a loss of more than a third of its population!); other cities have fallen similarly (though none quite so extreme) - other early-connected cities fell e.g. 1,702 to 1,425 and 1,285 to 1,047. It seems from looking at my savegames that the drop started sometime around the beginning of 1984. This is despite the fact that these cities claim to be growing at perfectly decent rates. From testing in other games, I've found that if I change the growth rate up to very fast, the large cities still can't even hold steady, while the small towns explode just like you would expect (80 > 500+ over maybe ten years).
This makes for quite a depressing game! Especially seeing as how I have no idea what's causing this. I'm wondering if JGRPP's day length factor is an issue, but I played a long game a few months ago with day length factor 5 and zero problems (though this was likely on an earlier version of JGRPP). Should I downgrade JGRPP? Is there something I'm doing wrong? What's going on?
(I can upload saves if needed.)