This patch might be the most meaningful one we've ever dropped. We listened closely to your feedback, banged our heads on the wall for a month to come up with the right solutions, and the result is a total revamp of the game's meta-progression system. With 52 new perks for a total of over 80, and a huge design improvement.
Perk System revamp
Dynamic perks
We're no longer locking you into pre-determined upgrades per king. You now have 9 slots. And you can use them in whichever way you want. The idea is to bring the 9 Kings core design to the meta-progression system. It's a minimalistic dynamic version of the game loop you're here for. The new system can be approached casually if you just want to chill, but that can have a whole new level of depth if that's what you're into. 
80+ upgrades
You will now have a limitless pool of perks to choose from, and they will be unlocked as you play the game. Some perks are universal, some are unique to your king, some are Rainbow perks. Think tactically and choose the best 9-combo for your strategy. We're starting with a total of 80+ unlockable perks and we'll keep adding more, and tweaking those that might not quite work yet.
Rainbow perks!
Rainbow perks will twist the game in interesting ways - including your own perk board (like Expander in the screenshot). Once unlocked, a Rainbow perk can be used across all kings, like Universal perks. We'll start with 3 experimental Rainbow perks and we plan on expanding the pool very quickly.
Unique Nothing perks
By the way, old "Nothing" perks are now called Universal perks. This means that our dear King of Nothing now has his own unique perk pool like all the other kings.
Level cap is gone
The 9-level cap is now gone. The community asked for it, and you can now level up forever. Every time you level up, you'll unlock a new perk as long as there are perks available. After that, you can still brag about being level 999 to your friends. The required XP to level up was also reduced by 25%.
A new perk every time you level up
If you're new to the game: you'll unlock a new perk, randomly, every time a king levels up. The unlock system will alternate between Universal and King perks. Every time you hit a level threshold for the first time (level 3, 6, 9, and so on), you will also unlock a Rainbow perk.
Early supporters in mind
If you're a veteran: those who've already played the game will start with one perk per level unlocked. All the perks you know are still available to be unlocked. You'll also likely have more perks than you did before. With the Universal pool of perks, the idea is to make the game less grindy while still keeping things fresh with the king-specific perks.
Difficulty Rebalancing
The game's core difficulties were rebalanced based on your feedback. On lower difficulties, first years got a little harder (Peasant difficulty is now equivalent to Squire, and so on). On the other hand, Endless Mode difficulty progression curve is now 10% less steep on all difficulties. King difficulty, the pure game experience, remains with a similar scaling, although you can now come up with more ways to beat it thanks to the new perk thresholds. It also means you can perceive the curve between difficulty levels with a bit more clarity (the gap between Prince and King being is now slightly smaller, for example)
The best thing about this rebalancing is that we're aiming to address two things we've been hearing from you: on one hand, it can be a little too easy to beat the core game on lower difficulties. On the other hand, some people feel Endless Mode gets way too hard too fast. By making the first years subtly more challenging on lower difficulties, we came up with a new progression curve that makes Endless years a little less abrupt. Don't be mistaken though: we're talking about 10%. It's still exponential ruthlessness. We'll keep tweaking everything according to the community's experiences. We are listening!
An important disclaimer
It took us a while, but we feel we finally cracked a balance between abundance and limitation. We truly believe that what makes 9 Kings special is that it forces you to be creative with a finite amount of resources (the magic number 9). But the 9 on its own wouldn't be any fun if it didn't enable hundreds of creative outcomes. We also really dislike the idea of mindless meta-progression. We want to value your time and make you feel stimulated, while giving you more agency. With this new system, we hope you'll see the 9-grid as a fun challenge, something that encourages you to explore, be strategic, and find the most meaningful perk strategy for your style.
Other Updates
As usual, here are the remaining updates of patch 0.7.91:
X-Ray now works with base cards
Slime performance improvement
Duplicated units are no longer (wrongly) affected by Populate.
Echoform/Slime will now properly duplicate extremely high stats (PENDING: HOTFIX INCOMING)
The game will now properly load extremely high stats (PENDING: HOTFIX INCOMING)
Ruthless can no longer insta-kill bosses.
Optimized Rainbow army shader
Dispenser projectiles are no longer underneath buildings (this dev wants to slap himself every time he sees a gameplay video of Dispensers in the last patch)
Perk art was updated
There's more coming very soon!
Don't forget to leave a Steam review
Anyway, we're very excited about this system and very eager to hear your thoughts. One of the biggest feedbacks we've got for 9 Kings was the lack of depth for the meta-progression system. And we agree! The game is in early access and hopefully we can keep building it together. We can't wait!
Please join us on Discord and Reddit. You can also find the 9 Kings wiki page here for information on the game! Love, Sad Socket team Steam Reviews: Your Feedback Matters We've been reading through all your Steam reviews, and we appreciate the feedback we've been receiving. We'd love to continue seeing more of your thoughts! It helps us know what to focus on for each upcoming patch.
Love,
Sad Socket team