I wanted to unlock some excess tiles in an existing city. "Lock all tiles" works as I'd expect. "Select initial tiles" also does as advertised: pick 9 tiles for free. Tiles beyond 9 cost cash from the current city's balance. "Unlock all tiles" does exactly that, and lets you buy as many tiles as you had unlocks -- but it charges for each tile, or each tile after 9 if "select initial tiles" is checked.
But the variant I was hoping to use was to buy as many tiles as an existing city already had bought for free. In this case, slightly fewer, to reduce upkeep cost from not yet exploited tiles.
There's two currencies involved here: tile unlock count and cash purchase cost. The mod seems to handle the unlock count well. And it charges for buying "new" tiles as the game normally would, which is good. With the use case of rebuying the city as it was before, there should be no change in the cash balance from the purchase cost. That leaves the cases where previously purchased tiles were relocked, but the city no longer has the money to buy them, even though they're free in the sense of the unlock count.
I'd like to see an option to allow free-in-cash-cost tiles up to the number of tiles the city already has unlocked (which may not be all the unlocks the city has earned through milestones, if those unlocked hadn't yet been used).
An alternative implementation to avoid exploits around switching to more expensive tiles would be to refund the purchase price of all unlocked tiles, and then charge (again) for all tiles purchased. In this case, there would be no 9 free initial tiles; their cost would be refunded and then spent again to rebuy those tiles, coming out to net zero. Purists might prefer the cost of the initial 9 not being refunded to avoid that tile-switching exploit, but that depends on the implementation being able to figure out which tiles where the initial 9 in order to know the cash cost.
