For those for whom figuring out how to use bitcoins isn’t challenge enough, there’s now Bitcoin Riddle.

A project by reddit user Fab1anFab1an, Bitcoin Riddle is to the diehard cryptocurrency fan what the New York Times Sunday crossword is to the more linguistically inclined.

“This is actually quite fun to watch,” commented Bitcoin Forum user Bitcoinm. “I’m surprised people are able to figure these out, most look pretty tricky.”

For each puzzle, Bitcoin Riddle offers an obvious prize: solve the mystery of the private bitcoin key, and the currency in the account is yours. Riddle Number Eight (“The Savage Beast”), for example, promised a reward of 0.2 BTC … around \$24 or a little over £15.

By all appearances, solving the riddles is not for the faint-hearted or numerically challenged.

“The Savage Beast,” for example, was “mind blowing,” wrote reddit user Bitco. “Got stuck analyzing the translations of hieroglyphs that mention hunting :p”

In addition to offering a bit of bitcoin to puzzle-solvers, Bitcoin Riddle also encourages site visitors to donate to the next pot at the bitcoin address 1PfE9rrwbimLa5xcpQpueLAhmEDBdwpHvU.

While each riddle starts with three basic clues, would-be puzzle-solvers can also access additional, bonus hints. For now, those extra hints are free, but it appears that Bitcoin Riddle will eventually start charging for those (a suggested price of 0.003 BTC, or around \$0.36 is given with one hint), with the funds going toward the next puzzle’s prize pot.

(And, yes, once the riddle is solved, the still-frustrated can view the solution online. For example, the answer to Riddle Number Six: “The Way of the Satoshi” — with the clues 1) 2.05, 5.50, 2) http://imgur.com/EsKlPig and 3) https://cryptobin.org/f250h2q1 — was “Leo & Victoria”. Getting that answer involved, among other things, identifying a Martian crater (“Victoria,” with the coordinates 2.05 and 5.50) and using the nonce value from bitcoin’s genesis block for decrypting on cryptobin.)

So there’s your weekend activity sorted.