Super Mario

King Boo and the Haunted Yard Expansion Set

A spooky little cul-de-sac with one genuinely clever trick up its sleeve.

Brick Rated Score

3.9/5

Set 71377 · 2020

Pieces431

Minifigsn/a

Year2020

Set number71377

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The verdict

The hidden mechanism in the shack is the whole reason to buy this one, and it delivers, you spin the wheel, a worm gear turns inside, and King Boo slowly gets teased up and toppled without you ever seeing the gears do it.

That kind of quiet engineering is what makes LEGO's game designers worth paying attention to. It needs the Starter Course to actually function though, and at this price for 431 pieces you're really paying for the surprise, not the brick count. Grab it if you already have Mario sets and love a good hidden mechanism, skip it if you just want a pile of parts for your money.

Best for: Super Mario theme collectors who already own the Starter Course and love a hidden-mechanism build

The full review

What it is

I love a set that hides its best trick where you can't see it working. That's exactly what King Boo and the Haunted Yard does. You spin the wheel connected to Swoops, a worm gear turns quietly inside the little shack, and King Boo gets slowly pushed up and toppled over to reveal the Super Star underneath. The first time I saw someone describe that mechanism I actually went back and reread it, because that's the kind of understated engineering that makes LEGO's Mario team worth watching. It's not flashy, it's just satisfying, the way a good magic trick is satisfying.

The catch

Now here's the part I'll be straight with you about. At 431 pieces for around fifty dollars, reviewers pretty consistently flagged that the price feels steep for what you get, and I agree with them. You're not paying for volume here, you're paying for one hidden mechanism and a handful of exclusive enemies. And it doesn't stand alone either, you need the Starter Course before any of this does anything at all, so if you don't already have that base set this isn't your entry point into the theme.

Who it's for

If you're already deep into LEGO Super Mario and you want the only version of King Boo that theme has ever made, this is worth grabbing, especially since it's retired now and getting harder to find at retail price. If you're new to the theme or just want raw piece count for your money, start with the Starter Course itself and come back to this one later.

The parts story

What the build is actually like, and the pieces worth knowing about.

Building this one feels less like assembling a big showpiece and more like solving a small puzzle box. The set runs off the usual grid a bit, with paths heading out at odd angles rather than the straight lanes you get in most other expansions, so it reads as its own little haunted cul-de-sac rather than a straight add-on lane. Along the way you're stomping a spider web, flipping a tree for coins, and knocking down two Goombas before you even get to the main event.

The real payoff is the internal mechanism tying the wheel under Swoops to the toothed bar that lifts King Boo. It's a simple idea, a worm gear plus a slowly rising bar, but it's built cleanly enough that it just works every time you spin it, no fiddly resets. King Boo himself is exclusive to this one set, so if you're chasing a complete cast of Mario enemies, this is a one time purchase. Four spinning Swoops and two Goombas round out the enemy roster, giving you decent play value even without a huge parts count.

Fun facts

01King Boo has appeared in exactly one LEGO Super Mario set, this one, making him exclusive to 71377
02The set requires the LEGO Mario Starter Course (71360) to function, it is not playable on its own
03The topple mechanism uses a worm gear to slowly and quietly lift King Boo before he falls, hiding all the moving parts inside the shack
04Unlike most Super Mario expansions that connect in a straight line, this set is laid out as an almost independent scene with paths running off at angles