I played Quacksalber three times on a review copy from Schmidt Spiele just prior to BGG.Spring, then played four more times at that show while teaching it at least ten times. Ideally I've honed my explanation to such a degree that the video overview below covers everything that you'd want to know — in fact, it will likely cover far more than you need to know as I throw in all sorts of asides about the nature of gameplay and how this title relates to others from Warsch.
The short take on the former topic: Quacksalber is a press-your-luck game in which you brew potions, pulling ingredients from your personal bag and adding them to your pot. In general, the more you add, the more points you earn and the more money you have to buy additional ingredients, which (could) lead to more points and money in future rounds. Pull too many of the wrong ingredients, and your pot overflows, which means you lose out of some of what happens later in the round.
As you might imagine from the description, your success in the game depends not only on what you buy but whether you draw from the bag what you bought. On top of that, did you draw the right things in the right order? Did the event card further give you a boost for the round? And what happened in the pots of your fellow players? The game is luck upon luck upon luck upon giggly snorting and table-slapping.
The short take on that latter topic: Ganz, Quacksalber, and The Mind all have a wide-ranging "playing space", by which I mean that the variability in how games play out seems larger than average. I've seen games of The Mind end on level 3 multiple times, and I've experienced around a dozen victories. Players in Ganz sometimes bomb out due to unlikely dice rolls and sometimes their score pinballs far over 200. A round in Quacksalber can end after four ingredient pulls in the worse case scenario — and I've seen it! — or a round can end with someone filling their pot to the brim, and I've seen that as well.
Aside from this wide range of game experiences, these three designs generate magic moments during gameplay when everything works out unexpectedly — and when the odds don't go your way, you marvel at what could have been. Maybe next time! Oh, next time starts in a few minutes? Well, let's give it another go!
(One rules correction for those who are playing this game: The official English rules for Quacksalber on BGG from Schmidt Spiele neglect to mention that each player starts the game owning one ruby.)