Many games, even those that aren't "role-playing games" per se, these days have game mechanics in which you get rewards for playing, and those rewards improve your stats and thus your chance of success when playing further. That leads to the weird dichotomy where people say they like games to be difficult, but actually spend most of their time in the game to get the rewards that make the games easier. If ever you face content in such a game that is too challenging for you, the best strategy is to go back to easier content and "grind" it for rewards that will help you to overcome the challenge.

To some extent this is also true for Card Hunter: The experience point system allows you to go up in level very fast (you get a full level of experience for beating an adventure 2 levels above your characters' level, half a level for beating an adventure of your level, but only 10% of a level for an adventure 2 levels below you); but if you were to consistently go for high-level adventures from the start, you would at some point run into difficulties due to a lack of gear. Running low-level adventures repeatedly will level you up a lot slower, but provide you with a much more extensive inventory of items which you might need later.

But Card Hunter doesn't work like typical MMOs, in which challenges are very similar to each other. In Card Hunter different adventures have different themes and different challenges, so the build with which you easily beat one adventure might not be optimal for another adventure of the same level. For example skeletons have armor cards that make them immune to piercing and slashing weapons, while slimes have armor that makes them immune to crushing weapons. Switching from an adventure against undead to an adventure in the sewers necessitates a change of weapons. And that is just one of many examples, there is also armor that helps you against specific enemies but isn't much use against others, and so on.

So what the devs from Blue Manchu wanted to avoid was somebody optimizing his build for one adventure, and then grinding that one adventure over and over to collect gear. It would be quite effective, but of the "optimizing the fun out of the game" variety. Thus in Card Hunter any adventure you finish becomes locked until the next day, forcing you to play different adventures. This effectively stops grinding. While you can play through many different lower level adventures in a day, they aren't pushover. And if you try adventures more than 2 levels below you, not only do you not get any xp, your characters are also automatically downleveled (which usually forces them to wear lower level gear as well).

I like the idea, but I was wondering whether a day lockout wasn't too much. Right now the adventures up to level 6 are kind of a tutorial and relatively easy, so new players tend to run into difficulties directly after that, in the level 6 to 8 adventures. While I don't think these adventures are inherently too hard, I do think that for new players it would be good to play through the lower level adventures more than once to stock up on gear. As it is, some people get frustrated because they can't beat the next adventure in the campaign (which you need to unlock further progress), but can't go back to lower levels either because of the lockout. Maybe a 1-hour lockout would work better to prevent people from grinding while still allowing them to play the same adventure more than once per day.