So in Dungeon World, the basic mechanic seems to be that you roll 2D6 + Modifier. If you get a 10+, its a 'good' result, and if you get a 7-9, it's an 'OK' result, with <=6 being 'bad/useless'. However, I don't see that there are enough consequences for bad/useless!
Let's take as an example Hack And Slash. The move works thusly:
When you attack an enemy in melee, roll+STR. On a 10+ you
deal your damage to the enemy and avoid their attack. At
your option, you may choose to do +1d6 damage but expose
yourself to the enemy's attack. On a 7–9, you deal your
damage to the enemy and the enemy makes an attack against
you.
So 10+ deals damage. 7-9 deals damage but suffers an incoming attack. <7? No effect. So oddly, it seems you suffer less damage with a complete miss than you do with a hit of some sort. On top of that, rolling <7 gets you free XP! What is the downside to players deliberately spamming moves that they know will not land in order to 'farm' XP?
Best Answer
On a miss, the GM makes a move. In particular, the GM is empowered to make a hard move, which includes just dealing damage! Of course, the response should be guided by the GM's principles, including make a move that follows (in the fiction). If you miss Hack and Slashing an orc, then it would follow for you to get hit by the orc. It wouldn't necessarily follow that a cave-in occurs, unless there's been some buildup in the fiction that a cave-in is about to occur.