Gameplay spec

What the player does, how the game answers, what is learned, how it is assessed, and what counts as mastery. Electron Dodger, in stage 2, is optional. Rewards stay off the critical path.

Hands

One set of verbs for the whole mission. Later stages reuse them on new apparatus.

Pick up. Hold a part. It lifts off the bench.
Pull a lead. Draw a cloth wire out of a coil. It sags.
Snap. Let go near a port. The plug clicks in. A wrong port still accepts it.
Unplug. Pull a seated plug back out.
Flip. Push the knife switch open or closed.
Try. Press the orange lever. The circuit attempts to live. There is no Submit.
Trace. Drag the lens along a wire.
Poke. Tap a drifting electron. It kicks along the stream. None of them is the correct click.
Mark. Slide a brass marker. It snaps to the nearest labelled tick.
Turn. Turn a clock hand, a current dial, or a unit ring.
Set wheels. Set the charge wheels on the jar before you run.
Decade. Click a dial through powers of ten, then one wheel for the front digit. Not a long crank.
Twist. Turn an arrow token that is already on the wire.
Pin. Tack a card onto the board.
Tile. Snap wooden words into a groove. Loose tiles do not lock.

No multiple choice as the way through a stage.
No Next button through a lecture.
No typing the answer into a form.
No clicking the one correct electron.
A wrong plug, a dark bulb, and a wrong decade are moves the game allows.

Response ladder

Fiddling is free. Picking up, unplugging, poking, and turning a part over never count as a miss.
A miss is a committed try: the Try lever, a released marker, wheels checked against the jar, a set decade dial, or arrows released.
First miss: consequence only. Nothing is marked wrong.
Second miss: one hint.
Third miss: a plain explanation. The player still does the action. Hearing it does not complete the gate.
Snaps and scale ticks are generous. This is not a precision test.
The street lamp and the closing cutscene never wait on a perfect run. An independent-mastery flag is not a lock. One short retry is offered and can be skipped. Skipping leaves the badge unearned and does not replay the mission.

Stage 0 · M1-A · not scored

The dark workshop

Player action: Walk the bench. Pick up the cell, the bulb, the switch, and a wire coil, and turn them over in your hands. Nothing has to snap yet.
Consequence: Nothing fails. Stalling is not an error.
Hint: If they touch nothing, Amp nudges the nearest untouched part.
Explanation: There is no lecture. If they still touch nothing, Ohm names the untouched object in one line — “This is the cell” — and waits. He does not define current.
Success: Each part has been handled once. Their jobs are felt, not defined. No equation appears.
Learning: A cell, a bulb, a switch, and wire are the pieces of this problem. Current is not named yet.
Assessment: Identify. Unscored
Mastery: M1-A handled, not graded
Reward: None

Stage 1 · M1-B

Make one light work

Player action: Pull leads out of the coils. There are only a few ports: cell, switch, bulb. Snap is generous. A plug will click into the wrong port. Flip the knife switch. Press the orange Try lever. Dropping a plug on the bench is not a miss. Unplug and rebuild as often as you like.
Consequence: Open switch, a gap, or the bulb sitting outside the loop: the bulb stays dark. Reversing the cell still lights a good loop. Polarity is not a trick here.
Hint: After the first dark run, the camera rests on the actual gap. No red mark.
Explanation: On the third dark run, Ohm says what a closed path is: the cell, wire, switch, and bulb must make one unbroken loop, and the switch must be closed. The player reconnects it themselves.
Success: The bulb glows amber. A short push-in, then a faint drift in the wire. Still unnamed.
Learning: A closed path lets something through. A break stops it.
Assessment: Diagram as a built circuit
Mastery: M1-B independent rebuild
Reward: None

Stage 2 · Look only · not M1-F

What is moving?

Player action: Pick up the lens and trace it along the wire. On the cloth the view stays dull. On the copper the view drops into the tunnel. Poke any teal sphere: it kicks along the drift and rejoins the stream. You are not choosing a correct electron. Then pull a short thread in the direction they move.
Consequence: Stopping on the plastic sleeve shows nothing moving. That is information, not a penalty.
Hint: The lens wants the metal, not the cloth. Offered only if they leave the wire.
Explanation: If they still miss the metal, Ohm says the moving charges are inside the copper, not the covering, and that in this wire they are electrons. The player still drags the lens there and points the drift.
Success: They watch the carriers and can point the direction those spheres move.
Learning: In this metal, the moving carriers are electrons, and they are negative. This picture is a model, not a true scale. No count. No formula. No second arrow.
Optional, not core: Electron Dodger. After the copper is visible, Amp can be steered between the drifting spheres. A few hits and he overcharges, the round ends, and he resets. Skip is always there. Not scored, does not change the circuit, and overcharge is not a science fact.
Assessment: Identify. Not the charge calculation
Mastery: Not a gate. Does not satisfy M1-F or M1-G
Reward: None

Stage 3 · M1-D · M1-C stays provisional

The meter

Player action: Pick up the ammeter. Unplug one lead in the live loop and snap the meter’s two leads across that gap, so the same current passes through the meter. Clipping both leads onto the bulb’s posts is allowed. When the needle settles, slide the brass marker. It snaps to the nearest labelled tick, such as 0.1 A. Release near the needle and it seats. You are reading a scale, not hunting a pixel.
Consequence: Across the bulb, off the loop, or on a dead branch: the needle slams or sits dead, and the reading is unusable. Ohm opens the trial. No explosion, no scolding.
Hint: After two bad placements, the loop itself brightens faintly so the missing place in the path is obvious.
Explanation: On the next miss, Ohm uses the textbook line: an ammeter is connected in series, so the current in the circuit passes through it. He does not place it. The player snaps the leads, then seats the marker on the tick.
Success: A steady reading in A. The bulb still glows. The number is about the flow, not yet a lecture on charge per second.
Learning: An ammeter measures current, and it has to sit in series. A bad placement is a bad measurement, not a secret wrong answer.
Assessment: Instrument use
Mastery: M1-D place and read without the explanation
Reward: None

Stage 4 · M1-E

Charge and time

Player action: Turn the current dial, or drop in a different cell. Turn the clock hand. Before you press the clock stem, set the charge wheels on the jar to your guess. Press the stem and watch the jar fill. If the wheels and the fill disagree, change them and run again. Later, one control is covered and you set the missing one. Turn the unit ring (A or mA, seconds or minutes) before the wheels mean anything.
Consequence: A wrong number does not dump the answer. The collector and the meter stay visible. A unit mismatch makes the glass and the clock disagree until the conversion is fixed.
Hint: Ohm asks which quantity changed. That dial glows. The relation is still hidden on a first run.
Explanation: On the third miss of a setup, Ohm states the relation they are in: charge is current times time, or the rearrangement they chose, and which unit ring to turn. They set the wheels again themselves. A later setup still starts with the formula hidden.
Success: At least two different setups are solved, including one rearrangement. The first prediction happens before any formula is shown.
Learning: Current is charge passing per unit time. I = Q/t, Q = It, t = Q/I. More current or more time means more charge. The sentence arrives after the glass has filled.
Assessment: Numerical. At least two setups, one rearrangement, one unit change
Mastery: M1-E without the formula handed over first
Reward: None

Stage 5 · M1-F and M1-G

How many electrons?

Player action: Two controls, not a long crank. A decade dial clicks through powers of ten. A second wheel sets the front digit. For one coulomb, the dial sits at 10¹⁸ and the wheel near 6. The swarm thickens to match. Then drop the wooden “electron” token onto the sample spoon. You never click one sphere as the answer.
Consequence: Counting specks one by one never finishes. The swarm compresses. A wild power-of-ten error replays the fill, slower.
Hint: Tiles for Q and e appear after a first guess. Pico pins the electron card when they choose it. Pico does not explain.
Explanation: If the dial is still on the wrong decade, Ohm states both textbook facts: each electron carries 1.6 × 10⁻¹⁹ C, and one coulomb is nearly 6 × 10¹⁸ electrons. He names the carriers. The player still sets the dial and the wheel, and still drops the token.
Success: A reasonable estimate, and a clear identification: those moving charges are electrons.
Learning: The charge on one electron, and that metallic current is mostly those electrons. The direction clash is visible and not solved yet.
Assessment: Estimation plus identification
Mastery: M1-F and M1-G
Reward: None

Stage 6 · M1-H

The arrows disagree

Player action: Drag two wooden arrows onto the wire and twist them. They may point the same way. Pour the plus-tokens into the model and twist the conventional arrow with them, then swap the tray for electrons and twist again. Pin three cards with tacks. Snap at most six word tiles into a wide groove, with one spare tile that does not belong. Loose tiles just sit there.
Consequence: Matching both arrows the same way leaves them overlapping and unresolved. The bulb still works, which is the point. Missing a card does not unlock the formal line.
Hint: Replay the positive-carrier picture once, then the negative one. The final sentence is not given yet.
Explanation: On the third wrong overlay, Ohm explains: conventional current is defined as the direction positive charge would move, so in a metal it is opposite the electrons. Both claims are true, and together they explain the opposition. The player still places both arrows and assembles the sentence.
Success: Electron arrow matches the drift. Conventional arrow is opposite. The three cards are connected. The sentence says conventional current is defined opposite electron flow in a metal.
Learning: Conventional current is the direction positive charge would move. In metal, electrons go the other way. This is the assertion-reason moment.
Assessment: Assertion–reason and a short constructed explanation
Mastery: M1-H arrows and sentence without the spoken answer
Reward: None

Stage 7 · M1-I

Asha’s lamp

Player action: Same hands as the bench, on the lamp post. A cloth plug is dangling: pull it and snap it into the open port. Snap the meter leads across a gap in this new loop and slide the marker to the needle. On the lamp’s own clock and charge wheels, set the missing time or charge. No question card appears.
Consequence: Same physical failures as the bench: dark lamp, unusable meter, a number that does not match. No return to a tutorial screen.
Hint: One visual clue only, after a real attempt: the loose wire, or the mismatched unit. Not both at once.
Explanation: If they are still stuck, Deepa or Ohm explains the open loop and the one relation, in two or three sentences. The player still snaps and still sets the wheels. The lamp lights either way. The closing cutscene does not wait. M1-I is a flag, not a lock: it is set only if this success did not use the explanation. Otherwise one short retry is offered, new numbers, explanation put away. The retry can be skipped. Skipping does not replay the mission. It only leaves the badge unearned.
Success: That one street lamp blooms. Asha’s stall is lit. Nothing else in the village turns on.
Learning: The same rules hold on a different circuit. Reaching the street is not mastery.
Assessment: Case and transfer
Mastery: M1-I is a flag. The lamp and the cutscene play either way
Reward: The lamp itself. No coins required

Stage 8 · Story · not a puzzle

Cutscene · what is pushing it?

Player action: Watch, or skip. There is no tool, no snap, and no right answer. Nothing the player does can solve it.
Consequence: There is no fail state.
Hint: None.
Explanation: If they ask what pushes the charge, the cutscene does not explain potential difference. Ohm says that is the next investigation.
Success: The question stays open. A quiet coin and a small workshop badge may appear if the mastery flags were earned. They do not unlock any science, and they are not required to finish the cutscene.
Learning: They can see and measure a flow. They do not yet know what pushes it. That question is the next section of the chapter, and it is not this mission.
Assessment: None
Mastery: Opens Mission 2. Does not add a gate
Reward: Quiet coin and workshop badge. They gate nothing