I really like this thread, because if we want game support to continue for a long time, there's going to come a point naturally where Frontier is supporting only the hardest core fans (hard corest fans?), and we need to be ready to continue to cheer Frontier and bypass the naysayers. It's also a bit tough to answer, because popular/unpopular can mean so many different things. Are we talking actual Sales? Reviews? Realism? Least controversial? Most consensus building? Loudest complaints from one part of the community (including my own part of the community - HA!)?
Like others here, any pack with animals in it is a must buy for me. I'm actually not even convinced that the single-family packs (primates, ungulates, reptiles, felids, canids) or specific regional packs would actually be less popular in practice, presuming that they each included the most popular examples of their kind. I guess it depends on what is meant by popular. Sure, the reviewers might not like them, and there would surely be some who complain. But I'm not convinced that sales for such packs would actually turn out to be less than other packs. Even an explicit all-clone pack would probably sell well if they manage to include all the most popular and requested clones.
And I think a domestic/petting zoo pack might actually turn out to be even MORE popular than some of our other packs, even if there are some reviewers or zoo specialists who might complain. Because I think that casual players who maybe aren't on these forums as much would totally eat that up!
I would definitely buy an exhibit animal pack! Although I'd love to see it could include a few more animals than normal, given that they're (presumably) easier to create. (I'm presuming that most of the updates to the mechanics would need to be in the associated update).
I personally would love a cetacean pack. I understand all the ethics concerns. But the zoo I grew up with when I was a kid (Indianapolis Zoo) had an oceans section that included dolphins, porpoises, whales and sharks, and I would love to be able to have these in game. And while there might be some who would boycott such a pack, and probably many who would complain or review poorly, I still have a feeling that it would end up selling fine in actuality.
A few packs that I'm not requesting, but would probably buy, include a recently extinct animals pack (say the last 500 years, so it could include the dodo), as well as a prehistoric pack (they could just import the species from jwe2), and even an alien/cryptic/fantasy pack. But again, these fall into the category of "I'd buy them if they came out", but I don't think these should be a priority.
For me personally, one of the hardest choices would be if they decided to do a scenery only pack, with no animals but only building pieces. I'd probably break down and buy it anyway, since I'd want to support the game and could probably justify it to myself that I'd end up using some of the pieces if I had them (which would probably end up being true).
I've even seen some suggestions of a ride pack or transportation pack, but to be honest I'm not sure if I'd end up buying that one or not. That may be too far for me.
By contrast, a plant only pack would be an instant buy for me, and probably many others on this forum, but might not do as well with casual players?
. I'm totally hoping we get an overhaul on vivarium design but I mean I really doubt it
