Marble Sort Level 399 Walkthrough Solution | Marble Sort 399

Marble Sort Level 399 Guide: The Locked Box and Mystery Column Trap

Marble Sort Level 399 hits you hard with a combination of hidden information and restricted access. You are looking at a board where half of your bottom targets are either locked behind a literal padlock or hidden completely. The dominant colors here are light blue, purple, mint green, and pink, but those are just the distraction. The real challenge is managing the flow of the board while hunting down specific keys.

You need to crack the center of the Top Tray to grab those keys, but the game deliberately blocks your path. If you just start tapping colors that look open, your Conveyor Belt will jam before you even thaw a single piece of ice. Let’s break down exactly how this board is rigged and how to bypass the traps.

The Restricted U-Shape Pattern in Marble Sort Level 399

This board is entirely dictated by its bottom Boxes. You have four columns, and three of them contain nasty surprises.

The far-left column starts with a Purple and Blue Box, but immediately hits a wall with a Pink Box secured by the Lock and Key mechanic. The second column is a solid stack of Green, Green, Green, and Pink. The third column is pure bait. It starts with a Blue Box, but underneath it is a punishing stack of three Mystery Boxes. The far-right column asks for Purple, Blue, Mint Green, and ends with one more Mystery Box.

Up in the Top Tray, the marbles are arranged in a chunky U-shape. Your immediate bottleneck is the bottom row consisting of dotted Green, Pink, Blue, and Light Purple marbles. Above them sits a tight cluster of Light Blue, Mint Green, and Dark Blue.

The keys you desperately need to unlock that left-side Pink Box are sitting on the Black and Orange marbles right in the dead center of the cluster. Two more keys are isolated at the extreme top-left (Orange) and top-right (Brown) corners. Meanwhile, the left and right flanks are completely frozen. You have a Red and a Green marble trapped in Iced Boxes on the left, and a Purple and Pink marble trapped in Iced Boxes on the right.

This layout creates a severe left-side jam risk. If you pull too many Pink or Red marbles before securing that first center key, your Conveyor Belt will fill up instantly.

Marble Sort Level 399 Step-by-Step Walkthrough

You have to play this board from the bottom up, ignoring the tempting flank colors until the center is entirely hollowed out. Keep your eyes on the Conveyor Belt space at all times.

Beating the Opening Bait in Marble Sort Level 399

The start of this level requires strict discipline. Do not touch the outer edges. Your only goal right now is feeding the top layer of the bottom Boxes to reveal what is hiding underneath.

1. Drop the Green and Blue center marbles. Tap the dotted Green marble into the second column's Green Box. Tap the dotted Blue marble into the third column's Blue Box. This immediately clears the path up the middle of the Top Tray.
2. Clear the outer Purples. Drop the Light Purple marble into the far-right Purple Box. You can now start feeding the far-left Purple Box to expose the Blue target underneath it.
3. Reveal the first Mystery Box. Clearing that Blue target in the third column is mandatory. Do this as fast as possible so the game flips the first Mystery Box. You need to know what color this column demands before you start pulling random marbles from the top.
4. Hold off on Light Blue. You will see several Light Blue marbles exposed in the lower-left of the Top Tray. Leave them alone. You do not have a Light Blue Box active yet. Pulling them now will permanently clog your belt.

Breaking the Ice and Finding Keys in Marble Sort Level 399

With the bottom center of the tray hollowed out, the dynamic of Marble Sort Level 399 shifts. You now have access to the mid-board mechanics.

5. Extract the center keys. You should now have a clear shot at the Black and Orange marbles sitting in the middle. Drop them onto the Conveyor Belt. If you have the matching bottom Boxes open, clear them immediately. Activating these will trigger the Lock and Key mechanic and finally unlock that stubborn Pink Box in the first column.
6. Thaw the Iced Boxes. Now that you are working deeper into the tray, start making matches adjacent to the left and right flanks. Clearing the marbles next to the frozen Red, Green, Purple, and Pink marbles will crack the Iced Boxes.
7. Clear the Green column. The second bottom column is entirely Green. Use the freshly thawed Green marble from the left side, combined with the Mint Green marbles in the center, to aggressively burn down this column. This creates massive breathing room on your board.

Surviving the Late Game Mystery Board in Marble Sort Level 399

The final phase is a memory test. As you clear the second and third columns, you are going to reveal the remaining Mystery Boxes.

8. Prioritize the revealed Mystery targets. The moment a Mystery Box flips and shows its color, scan the high corners of the Top Tray. Drop those exact colors immediately. Do not let revealed boxes sit empty.
9. Grab the corner keys. Your very last targets should be the top-left Orange and top-right Brown marbles. These hold the final keys. Because they are at the absolute peak of the U-shape, you can only safely pull them once the main center mass is completely gone.
10. Flush the remaining Pink and Red. With the Pink Box unlocked and the Mystery Boxes identified, dump your remaining top-edge Pink and Red marbles into the first column to finish the board. Keep your belt organized, match in sets of three, and the level will clear.