Right now each "hand type" has its own star for upgrading but they don't affect each other. Often times I will start building a deck around some concept, for example a straight, while I'm slowly changing the card suits each run. I then get to the point where I get a lot more straight flushes, but because they're on a completely different upgrade path, they're actually worse. It feels wrong. It feels like when I upgrade straights it should also affect straight flushes. Imagine if instead of having Neptune as a card you'd have to upgrade both flushes and straights, each one providing some benefit. Or instead of Ceres you'd have to upgrade both flushes and full houses. It means that your deck can slowly develop and naturally evolve and also that for tougher hands you have to get two star types to upgrade it - which maybe makes them feel even more valuable.
#modular upgrade paths
wise panther
potent timber
feels broken
wise panther
feels broken
I mean you'd have to balance it, but also it means for flashier hands you'd have to get two stars for an upgrade so it's already nerfed a little in a sense
fossil nexus
I think that it could be pretty fair if the "composite" Poker Hands could gain levels from every second (of maybe third) Planet bought for the Poker Hands they are made up from. E.g. you buy 3 Straight and 1 Flush Planet and Straight Flush would gain 2 levels. Since you still gain a whole level instead of every second from buying the Straight Flush planet you would still do that if given the choice if you have already transacted to playing that as your main Poker Hand. Some Composit Poker Hand's scaling might need to be brought down a bit to compensate though.