In Hammer Time (@HABA_usa), you bash the box w/ a hammer, trying to dislodge gems that match what's depicted in your cart. Collect joker gems by meeting the current challenge of knocking off 6-8 gems, an odd number, 2 black gems, etc.
— BoardGameGeek (@BoardGameGeek) July 19, 2021
BGG game page: https://t.co/zUFhaXdrRc —WEM pic.twitter.com/kXFlOUn2iL
Do I need to say more? I'm not sure, but just in case, here's a bit more:
Each player has four mine cart cards, each showing 4-6 gems. On a turn, you hit the box with the hammer, after having rotated it in whichever way seems optimal, and as long as you don't knock off more than eight gems, you take any gems that match those depicted on your topmost cart card and fill those spaces, with white gems being jokers. Return any other gems to the top of the box. (If you knocked off 9+ gems, return all of them since you're a brute and not worthy of claiming anything.)
Additionally, if the gems you knocked off match the current task card — knock off an odd/even number of gems, knock off 1-3/6-8 gems, knock off two black gems — then claim that card, which counts as a joker.
If your cart is now full of gems or you can use claimed task cards to fill it, set that card aside and reveal the next one, returning all gems to the top of the box. If you've claimed your fourth cart card, you've probably won — unless someone else also claims their fourth one the same round, in which case you compare completed task cards in reserve.
Hammer Time is a concept game that challenges you to compete against others in a task that you would be unlikely to encounter in any situation other than a game. I mean, that's true for pretty much any game, but aside from Toc Toc Woodman, a.k.a. Click Clack Lumberjack I can't think of other games in which you're asked to dislodge game bits in just the right way.
I've played Hammer Time twice on a review copy from HABA with gamers who are far older than the suggested lower age limit of 5, and it works well for what the designers are trying to do. I offer more thoughts about the game in this overview video: