Played through more of Challenge Mode today, reaching Level 13, which is completely and utterly impossible.
I also played a few more games with my wife, and then a few games online with random people. The online games weren’t particularly successful, as people kept quitting. In fact, in one game that I was hosting, some other guy left and I got a message telling me the game had ended because the host had quit. But I was the host. And I certainly didn’t quit.