🔩 Robot Lab Screw Masterbuild

<p>Robot Lab Screw Masterbuild hands you a rack of threaded bolts in the robot lab, each stacked with mismatched coloured nuts, and one beautifully simple rule: only the top nut of a bolt can move, and it will only screw onto an empty bolt or onto a nut of its own colour. Lock three of a colour together and that bolt is done with a satisfying click. It is the puzzle mechanic that conquered 2025-26, and the depth sneaks up on you — every unscrew uncovers what was hidden beneath, and the two spare bolts are your only working room. This is the fiendish tier, where ten colours leave zero slack for wasted turns. Every level is checked by a solver under exactly the single-nut rule you play with, so a clean solution always exists and a fair turn target is set for three stars. Undo forgives slips, nothing is timed, and it is free and instant in your browser.</p>

How to play

• Tap a bolt to lift its top nut, then tap another bolt to screw the nut on.
• A nut only fits an empty bolt or a nut of the same colour.
• Lock a bolt by stacking three nuts of one colour — locked bolts are done.
• Sort every nut so all bolts are locked or empty to win.
• Beat the turn target for three stars; Undo takes back a move.

Controls

Tap or click a bolt to pick its top nut, then tap the destination bolt. Undo and Restart sit under the rack.

Features

• 7 solver-verified fiendish levels in the Robot Lab workshop
• Single-nut moves — the exact rule the solver proved solvable
• Chunky 3D-look hex nuts and threaded bolts, crisp on any screen
• Undo, star targets and a global + daily leaderboard

FAQ