How to plan moves ahead in a tile puzzle: six checks, and Millrace's Level 1 move by move

Millrace is a tile-delivery puzzle: build one exact value on one marked cell inside a move budget, while tiles keep arriving through a single inlet on the board’s edge. The board is fixed and every arriving tile is shown before your first move, so a level can be planned to the end. The campaign screen states the core rule in one line: “Tiles keep arriving at the marked cell. Block it and you lose.”

The rules that matter for planning

Six checks before every swipe

1. Read the chapter as a number. Each chapter is pinned to one solution length. Every Warm-up level’s shortest solution is exactly 5 moves, Tactics 6, Pressure 7, Precision 8 and Deep Water 9; Mastery runs from 10 to 16. Compare it with the “moves left” counter before your first swipe: a Tactics level that opens with 8 moves left gives you two spare moves.

2. Do the target arithmetic. Every tile is a power of two, so the target is built from pairs: a 32 is two 16s, a 16 is two 8s. Before moving, find the tiles that will become the target, including any still in the queue. Note anything that could merge with the finished value, too.

3. Never slide toward the inlet’s edge while a tile is due. After every arrival, the newest tile sits on the inlet, against the edge. A slide toward that edge can’t move it off. It either stays put or absorbs an equal tile behind it, and either way the cell is still occupied when the next tile comes. So from move 2 on, while the queue isn’t empty, that swipe does nothing, loses, or wins. It can win because the goal is checked before the next arrival, so a slide that completes the delivery still counts. No level is an exception.

4. Check the inlet’s own line on the other slides. Say the inlet is on the left edge. Left is check 3. Right moves the newest tile away, unless its row is still full after merging. Up and Down pack the inlet’s column toward one end, and if it holds enough tiles after merging to reach the inlet, one of them lands on it. Count before you swipe.

5. Count the queue. Each level card shows how many tiles are arriving, and the status bar under the board shows the remaining queue with the next tile highlighted. One tile arrives after each move until the queue is empty. Level 1 has three arrivals and a 7-move budget, so the inlet matters for the first three moves only. After that, the board is a pure delivery problem. In 9 of the 64 levels the queue holds at least as many tiles as the budget has moves, so the inlet never stops mattering.

6. Choose your finish early. A delivery ends in one of two ways. Either you build the value elsewhere and slide it onto the vault, or the final merge happens on the vault itself. In 22 levels every shortest solution ends with a slide, in 29 with a merge on the vault, and 13 can be finished either way. Carrying needs an open lane to the vault; merging there needs the second tile to line up with it. The early moves build one or the other.

Level 1, move by move

Here is the first Warm-up level’s starting board:

The inlet is on the left edge, second row; the vault is directly below it. The target is exactly 16. The queue is 2, 2, 2, and the budget is 7 moves. The shortest solution is 5 moves, and only one five-move line exists.

Start with the arithmetic. 16 is 8 + 8, and the second 8 can come from the two 4s. The three queued 2s play no part in the target. They are the cost of the level: three tiles to keep off the inlet.

The 16 is built in the far corner, away from the arrivals, and carried to the vault only after the queue is empty. That is check 5 and check 6 working together.

Where it goes wrong:

• Move 2, Left or Up: Blocked. Two of the four swipes lose on the spot. Left pushes the 2 that just arrived against the edge (check 3). Up packs the left column, the 2 on the inlet and the 4 in the corner, into the top two cells, which puts the 4 on the inlet (check 4).
• Move 3, Up: lost, quietly. Up is legal and blocks nothing. It splits the two 8s: one goes to the top of the third column, the other to the second row of the fourth. With four moves left, no line brings a 16 to the vault. Nothing on screen says so, but if the run ends in a loss, the card reads “Position lost at move 3”.
• Move 3, Down: safe, but slower. It still wins, in six moves instead of five, so it costs one of the two spare moves.

Level 8: when the queue never runs out

Level 8, in Tactics, turns check 5 around. Nine tiles are queued against an 8-move budget, so a tile is due after every move the level allows. The inlet is in the top row, second column, and the vault sits right next to it in the third column. The target is exactly 32.

The only shortest line takes six moves: Right, Down, Left, Down, Right, Up. Its last swipe goes toward the inlet’s own edge with four tiles still waiting. That’s the exception in check 3. Up carries a 32 from the third row onto the vault, and the goal is checked before the next tile is due. The same swipe one move earlier would have lost on the spot.

Why the checks are not enough on their own

Every check above looks one move ahead, and one-move play is what the levels are built to beat. Before a level ships, 280 strategies that never look past the current move play it, among them 24 versions of “keep the inlet clear”, 24 that refuse any move that loses at once, and 24 that steer the target toward the vault. If any of them wins, the level is thrown away; how Millrace’s levels are made covers the full battery. The checks keep you alive. Solving takes the next step: where the tile after next will land, and what the board must look like when it does.

When you get stuck

• Hint draws the first move of a shortest line from where you stand, with a one-line reason. It runs the same solver that verified the level, and it’s free and unlimited.
• Undo inside a level is free and unlimited. After a loss, the card’s main button is “Undo that move”, not Restart. Undo tokens apply only to Freeplay, the endless board.
• The result card says “Best possible is N moves” when you solved a level in more moves than it needed.

Millrace is free on iPhone and iPad, with no ads and no lives; the app page has the full rules. The comparisons with Threes, KAMI 2 and Flow Free set out what each of those games asks of you.