Zerdly

Chain Reaction Studio

Read the goal card, place parts on the board, wire switches to doors and fans, then press Run and watch the chain reaction.

Loading Chain Reaction Studio…

About Chain Reaction Studio

Chain Reaction Studio is a contraption puzzle set on a toy-lab pegboard. Each challenge gives you a goal card - ring the bell, fill the cup, light the lamp - some fixed parts, and a small kit with a part budget. Every part has labelled ports that say what it takes in and sends out: contact, roll, pulse, air or pull. Switches send a single pulse along a wire, and doors, fans, coils, splitters, lifts and lamps react to it.

The machine runs in a fixed-step simulation (240 steps a second) that does not depend on your screen, so the same machine always does exactly the same thing and the replay matches the run. Every challenge ships with a stored reference machine that the site's test suite runs to prove the goal can be reached, and also checks that the board cannot be solved with no parts at all.

How to play

  1. Start on the Guided Bench: five short lessons on ramps, dominoes, seesaws, switches and doors.
  2. Read the goal card at the top. Ticks appear as each part of the goal is met.
  3. Tap a part in the tray and tap the board to place it, or drag it straight from the tray. Drag a placed part to move it.
  4. Tap a part to open its inspector: rotate it, change its length, mirror it, set its power, or wire a switch to a target.
  5. Press Run. If the machine fails, a coach note says what happened last and a marker shows where it stopped.
  6. Stuck? The hint ladder goes from where to look, to what is missing, to a ghost part, and finally the full reference machine.
  7. Watch any run again in Replay Theater: scrub, slow it to a quarter speed, step frame by frame or follow the ball.

Controls

  • Mouse: left click to place, select and drag parts; right-drag to orbit the camera, middle-drag to pan, scroll to zoom.
  • Touch: one finger places and drags parts. Turn on Camera mode to orbit with one finger and pinch to zoom with two; the view buttons on the right also orbit, zoom and reset.
  • Keyboard: N and P select parts, arrow keys move (Shift for bigger steps), Q and E rotate, F mirrors, + and − change length, W starts wiring, Delete removes, Ctrl+Z and Ctrl+Y undo and redo.
  • Space runs or pauses, R resets, the right arrow steps one frame while paused, H gives a hint and Escape pauses or closes a panel.

The rules

  • Each challenge has a part budget and a kit: how many of each part you may place. The part counter turns red if the machine breaks a rule, and the list says why.
  • Parts may not overlap or leave the board. A wire runs from a switch to a part with a pulse input and can be at most 8 board units long; a switch can drive three wires.
  • Fans and coils never add free energy: a fan blows for 3 seconds per pulse, a coil pulls balls only and is capped. Bumpers return 85% of the impact speed - never more.
  • A run ends when the goal is met, when nothing has moved for three quarters of a second, after 20 seconds, or when a ball enters a red no-go zone.

Scoring, saving and limits

Solving a challenge earns one star, one more for using no more parts than par, and one more for reaching the goal within the par time. Your best stars, parts and time are kept for each board.

Your stars, the machine on each board, up to forty saved machines and your settings are stored in this browser only. Nothing is uploaded and there is no online leaderboard. Clearing this game's data in Settings does not touch any other Zerdly game.

Machines are limited to 30 moving bodies and 20 seconds of run time. Imported .zchain files are plain data: the whole file is refused, with a reason, if it is over 200 KB, from a newer version of the game, or has anything unknown, out of range or malformed. The Daily Contraption is picked from today's UTC date and is the same for everyone.

Accessibility

Every action is a real button with a label, reachable with the keyboard; the canvas is never the only way in. Parts can be placed, moved, rotated and wired without a pointer, and goal progress and results are announced to screen readers. Settings include reduced motion, sound (off by default) and graphics quality.

Questions

Is every challenge solvable?
Yes. Each one ships with a reference machine that the site's automated tests run to the goal, and the last hint can show it to you.
Why does my machine always do the same thing?
The simulation uses fixed steps independent of frame rate, so the same parts in the same places always give the same run and the same replay.
How do I share a machine?
Open Save (My Machines), save the machine and choose .zchain to download it as a small file. Anyone can import it on their own device; nothing is uploaded.
Is this the same as Domino Chain Studio?
No. Domino Chain Studio is about domino runs. Chain Reaction Studio is about mixed contraptions with switches, wires, doors, fans, coils and lifts, built to meet a goal card with a part budget.