Yes. It means if you want to play the game "correctly", you have to do it their way and abide by their constraints. There's no GM discretion on what to do, just on how. At least, that's how it's always read to me.
Except those aren't constraints. They're simply the same things that every GM does, but written down in a handy bulleted list.
Here's the list from MotW:
Every time it’s your turn in the conversation to tell the hunters what happens, or when they look at you expecting you to say something, use one of these moves:
• Separate them.
• Reveal future badness.
• Reveal off-screen badness.
• Inflict harm, as established.
• Make them investigate.
• Make them acquire stuff.
• Tell them the possible consequences and ask if they want to go ahead.
• Turn their move back on them.
• Offer an opportunity, maybe with a cost.
• Take away some of the hunters’ stuff.
• Put someone in trouble.
• Make a threat move, from one of your mystery or arc threats.
• After every move, ask what they do next
Separate Them: Ever had a bridge break when only have the party has crossed over? Heck, AD&D has a "bend bars/lift gates" roll just for those times when a portcullis crashes down between the party, stranding half on one side and half on the other.
Reveal Future Badness: If you've ever had the party come across the clawmarks of the creature they're hunting, or a puddle of blood, or an unhinged message scrawled onto the wall, you've revealed future badness. The whole "Signs" section in each of Level Up's monster entries is about how to reveal future badness.
Reveal Off-Screen Badness: If the PCs ever hear a scream or the sounds of battle, that's this: Something is happening
right now, and the PCs can react to it.
Inflict Harm, as Established: If you've established something, like an environmental hazard, can be dangerous, you probably actually make it dangerous, right? And that means inflicting damage--or exhaustion/stress, in Level Up.
Make Them Investigate: Ever hide clues? Put a secret door or compartment in an area?
Make Them Acquire Stuff: I'm sure you've had adventures where the PCs need to get X before they can do Y.
Tell Them The Possible Consequences And Ask If They Want To Go Ahead: "Are you
sure you want to do that?" is one of the most important GM phrases out there. I'm sure you've used it.
Turn Their Move Back On Them: This one isn't obvious, because D&D doesn't use moves. But what it means is to make what they're trying to do dangerous or backfire in some way, even if only in response to a bad roll of theirs.
Offer An Opportunity, Maybe With Cost: I'm sure you've done this as well. The PC can grab the jewel. The PC can either grab the jewel
or help their friend, but not both. The innkeeper will allow the PCs to stay for free,
if the bard performs to their satisfaction. Things like that.
Take Away Some Of The Hunters' Stuff: This is literally built into Level Up's exploration challenges, where poor rolls cause a loss of Supply. But there's a good chance you've broken their weapons and tools (maybe a crit fail on a lockpick roll causes the pick to break), or had their stuff stolen by thieves, mischievous fey, and so on.
Put Someone In Trouble: If you've ever had the monsters focus on one PC, you've done this. If you've ever had an NPC ally get in trouble, you've done this. If you've ever had hapless NPCs be threatened and in need of rescue, you've done this.
Make A Threat Move: If your adventure notes (whether ones you've written or ones you've bought) has had things like random encounters, notes on how specific creatures might react, traps, hazardous areas, moving threats, etc., you've done this.
And then there's
soft moves and
hard moves, which is the difference between "You see an orc with his sword in his hand; what do you do?" and "As soon as you spot the orc, it raises its sword and charges! Roll for initiative."
Anyway, as you can see, there's no constraints here. It may seem weird to see them all spelled out like that--it was a bit weird for me, the first time I saw it--but it's literally all the same things all GMs are doing anyway. The only difference
is that it's spelled out, rather than being scattered across books, old Dragon Magazine articles, and blog posts, or being learned through trial and error. And it's not a constraint because you're not limited to that list. If you can think of something else to do as the GM, go ahead. Daggerheart has a somewhat different list of GM moves, including (but not limited to) things like "Show How The World Reacts" and "Use a PC's Backstory Against Them", which, again, are things I'm sure you've done at least once.
