Thanks for your thoughtful feedback. Don't worry, I am all around happy with it. There is so many valuable stuff that gives me reason for some good, deep thinking.
When making decisions, I constantly have some of my favorite games in mind. There is this one in particular, where the world is designed, but the loot is random - it's The Long Dark. But many more factors in that game contribute to such a mix feeling "just right", and 9 Dayz is missing a lot of them. It is indeed intended to be damn hard, but taking TLD as a success model, this game offers different play modes - from something like "let's take a cozy walk in a snowy forest" to a never-ending survival battle ala "oh my god, if I can't start a fire in the next 2 minutes, I am done for sure. oh no! there is a pack of wolfs!" :-D
The cluttered UI... yes. I find no good solution for too many Cards piling up in certain places - game is removing them after a certain distance, and players have to re-discover them. But still - maybe I have to reduce the threshold when a certain amount of Cards is exeeded. Removing the info icons and additional texts is something I want to avoid, that's a personal preference and something I am missing in many games and UIs in general.
And the numerous systems will probably even grow in numbers. Truth is, I am not good with designing clever, neat, minimalistic game mechanics. To me this is the supreme discipline of game design only very few people master. The only way I can work around this lack of skill is by staying on the "real" side. Which means, at one point my game will also offer a fishing mechanic, cooking, luring etc. But all of them will have this Card-based twist, which I hope will bring up some fresh, new variants of these established mechanics.
Thanks again for sharing your thoughts. Really appriciate that!