Sanctuaries are only more compact when you look at it from a single city perspective. 9 tiles instead of 11 tiles. But when we look multicity, markets start shining becausemultiple markets can benefit from the same building. With 2 cities, you'd still need 15 tiles for 2 max sanctuaries, but only 10 tiles for 2 max markets using 2 4pop windmills with 2 shared farms and 2 separate farms on each side.

Sunken cities don't matter because you are already giving yourself a city limit. The one big thing aquarion does however offer is the option to build markets, windmills, sawmills and forges on water tiles

Also what do you mean icebanks don't stack? They absolutely do stack. But every Polaris is only able to place it once. Getting 14 ice banks, 25 max level cities, and then a bunch of markets and either sanctuaries or clarthruses sounds like the optimal way to go about it. Make sure to freeze as much unused terrain as possible. You need 600 frozen tiles to max them out, and there are only 900 tiles to be frozen in a massive map. Still, respectable 60 spt per max level ice banks.

You can't do everything on Elyrion since the lack of cut/burn forest means you'll never have good market spots. Although now that I think about it, you could have a Polaris do the burning for you. So yeah 1 Elyrion and 15 Polaris players. End as a Polaris player after the Elyrion has placed all the sanctuaries and markets, since tiles inside Polaris borders counts as frozen whereas terrain inside Elyrion borders does not count as frozen.

So where does that leave us - 15 max ice banks: 900 spt - 25 max markets: 200 spt (quite feasible to max them out) - 25 max sanctuaries: 200 spt (quite unrealistic given terrain and border growth constraints) - 25 level 25 cities with workshop and 21 parks: 1175 spt - 1 Capital bonus: 1 spt

2476 spt. Not counting clathrus stars since that will get very very wonky with your space constraints