Suggestions for difficulty balance: the challenges feels more like a puzzle, where when you find the correct build and/or gameplay style, they became quite easy and you are able to complete them consistently. The problem is the price to figure them out is to high. Give us a practice mode for them. Maybe the goddess want to mess up one with another, and one let us practice the challenge of the other, without costs neither rewards. Maybe in the training there is less balls to collect and less bits to kill, so the challenge still feels like a challenge when we try to complete it after practicing a bit.
For my experience, "bit magnet" is the most essential card; but that's not intuitive. I only tried it farm bits more quickly, but it soon became obvious it is need for max level and even for one of the challenges. I think collecting bits for reducing the time to get the balls is very important, but actually collecting the bits in the chaos of the battle is overwhelming, and probably leaved behind for many players. I would guess that buffing a little bit the base radius of bit collecting (without the card) would be a discreet change that would make the game easier to reach max level, without changing to much the game fundamentals, neither feeling like the dev is taking you by the hand.

I also think the challenges should feel more optional (and I am certain they will feel more optional already when they aren't the novelty of the month anymore). While in my opinion the private rooms are good optional content and are fine as a reward for the challenges, there is an argument to be made that porn should be easily accessible in a porn game. And the surges does not feel like optional content imo, they feel like a upgrade that we should be able to get way earlier. A upgrade that could potentially make the game easier shouldn't be a reward for those who already think the game is easy enough to reach max level; there is no impact for those people, while is missing for those that are still founding it hard to progress. What I think feels way more like a optional content would be some (much needed) character customization option. Some new colors or painting designs that are locked behind a difficulty challenge, to be wielded only by those who deserve it. Maybe even rescue that old idea for masks...?

And, of course, I will repeat once more: upgrading a character or a card should be less grindy. There is no need for the game to be so much grinding, because the game is fun, it will already capture players without the grinding. With some math (~250 cards, 10 for max level, ~12 cards (3 packs) each 80 minutes (8 runs, a day reset)), you need at least 280 hours to max the level of all cards. You don't need to max the level of every single card, but you probably will not max out not even the ones you want because of RNG. Give us more cards per minutes, and give us less RNG-dependent ways to upgrade the cards. Getting good cards is absolutely necessary for max level and for challenges, and I would bet many of the players complaining about difficulty do not have the necessary cards, because the grind is this much. Less grind is more players meeting the requirements, and less complaints.

If the IA of the dolls were a little better, the game would also feel better, but I guess thats a whole different beast, not so easy to adjust; but maybe this other changes would not be so hard.

Anyway, I still think this update was great, I love the new challenges and for me (~40 hours of gameplay on version 6) they weren't that hard at all, and were extremely welcome. Those suggestions are only because I'm seeing the backlash of the challenges and you said you want to re-balance the difficulty, so why not give some suggestions. I hope I'm not being to invasive, and I trust the work of someone who made such a great (although not without some problems) game.

I think Ciella's Challenge is way too difficult, I can understand gathering balls alone with a bad weapon card, but the amount of enemies and gigabytes it throws at you are way too much for it to be plausible in my mind, I can barely get two out of the three balls needed to even beat it the first time (I haven't even been able to beat it and I sure as hell am not wasting levels on good cards bashing my head against it until I do), and any amount of enemies I do defeat are always immediately met with many more dropping at once, there is no time to actively open the firewall while holding off a force that relentless, even with gigabyte resistant upgrade cards, Meira's Challenge is much more fair in comparison

developer ,difficulty 100, seriously .....??? Are you playing your game?How am I supposed to do it all in a minute when there are too many enemies!!!!!? Make a balance! It's impossible to get through! If I get 5 pushers all the time .Bots are useless and constantly dying! Fix it all!!! It is impossible to live to 100 .even with top cards! There are too many enemies and push!!! (translation.ru)

i download the new 6.3.2  but my game stated  lagging or freeze  anyone have same problem

The update is nice , but how it is possible to reach dificulty 100 , I played a lot and I reached only dif. 55 , are there some trick or mecanics that I don't know ?

Looks like the movespeed in Glitch City was increased, which was such a great QoL change, navigating through the city now feels so much better!

The new challenges are also such a great addition. Unlock them gave me a new objective in the game, and once they are unlock, they are fun, hard in the right way, and gives a much need gameplay variety. 

The new surges are also amazing. I didn't really care about the surge system before, because I think the first one is weak, and I couldn't bother getting out of my way to charge a doll. The news surges are quite strong, but I still don't wanna to charge each doll after any game, so I still not using them so often.

Private room are fine. I think they could be better, considering how hard is to unlock them. But it's ok.

At first, I thought the twice-daily reward would be a great new way to collect some cards, but is not so good for this for what I redeemed until now. For me, the best reward are the buffs. They are great, but is not something I think the game was in need.

Selling cards is not a system with I think I will interact. Collecting cards in this game is my objective and also my hell. I wouldn't get rid of any of my cards, specially for some bits. But I guess there is some players that will enjoy this new system.

My biggest complaint with this update has to be the challenge cost and the money reward. As I said, collecting cards and maxing out their levels is my biggest objective and the game, and the rate of completion of such a challenge is limited by how many cards I can buy per day and by RNG. Mainly because of RNG, to lose a level in a strong card that I needed so much time to upgrade feels bad. To much bad. I get the challenge need to have increased risk, but I think this to much.

And the money reward... I think in the late game, we have money (or bits) in excess, so is rare that a big money reward feels appetizing. So, after getting the surge and the private room, getting money is not enough to make me want to replay the challenge, specially with such a high risk involved.

My suggestion is to have a wild card as a option of reward for the challenge, and also for the twice-daily reward. You would be able to convert this wild card in any card you want, or maybe to upgrade any card you want without the risk of the upgrade transforming the card.

My other suggestion is a new building to manage the dolls, like we had back on 4.x. Not to remove the option to interact with them on Glitch City, but to centralize the options (maybe only after a certain prisoner rank) of customizing and sending to bath. This build should also have the (already existing) option to accelerate the bath, and to immediately charge all the dolls for some amount of money, so we have something to do with the money in the late game.

Great update in general, the game feels much better with it. Great work!