What is crunch?
Crunch is when developers are forced to work extra hours on a game, often uncompensated. It can lead to negative health impacts for the developers.
You can read more on this Wikipedia article, I used it to form this answer.
Hope this helps :)
That's actually a good question that should have been answered already in a challenge entirely based on not doing it ^^
It's an important topic and even if the concept exists in many industries, it's known as "Crunch" in the game industry. It's basically an abnormal and unhealthy exploitation of the workforce. Instead of having people work for a normal amount of work each day and each week, you have people working for more than expected, sometimes way more than expected, (and the extra hours often aren't paid). Most of the times it happens near the end of development. Even if it's sometimes said that people working that long agree with this practice, they mostly agree because if they disagree they might be let off, miss opportunities or even have the project they work on fail. It can be caused directly by a lot of factors, bad management, bad work environment, lack of resources etc. But ultimately it's a culture that has been built through the years, that makes people see crunch as a normal thing to do instead of actually finding proper resources, good management, good work environments, or just taking time, moving the deadline/reducing scope. Even us, independent developers, tend to think that crunch could be justified if it's for passion or for a contest. Most of the gamejams suffer from being overly competitive, pushing you to use any second of their short duration to get better results and thus, reinforcing the crunch culture.
Then, "Crunchless" would then mean that you defined an healthy schedule and never had to work more than what you planned, even near the deadline. It's as much challenging your execution skills as your scoping, planning and management skills.
If anyone want to add to this attempt at defining "Crunch", please do. It's something that has been, fortunately, quite covered since it's a problem that affects most of the big game companies, so you might not have issues finding articles about it and other people defining it. I hope it answered it, let me know if anything's still unclear.