How the PRD was designed

Final. The path from the two source documents to the site the team will build from. Screens, the map, the spec, and the handoff are the PRD. There is no separate PDF. Electron Dodger is optional. The rest is core.

Locked direction

05 · What the game is

Mission 1 is called Make the Bulb Glow. A Class 10 player arrives in Spark Village at dusk, during a blackout, and is asked to restore one useful light. They play as Wonder or Arav. Professor Ohm does not teach the chapter. He sets up experiments and asks what the player just saw.

The mission is an investigation: build a circuit, watch the bulb, look inside the wire, measure the flow, play with charge and time, then find out why the diagram arrow points the other way. When that is understood, one street lamp comes on. The clinic, the school, and Bina’s pump stay dark on purpose.

It is not a worksheet, a lecture, a quiz room, or a coin grind. Story is the reason to try the experiment. The picture comes before the sentence.

06 · What the student takes away

The goal is visual understanding, not a recited definition. By the end, the student should be able to do these without a tutorial sitting on the screen:

See a closed path. A complete circuit lights the bulb. A gap, an open switch, or a loose wire leaves it dark.
See the flow. Current is charge passing a point over time. In a metal wire, the moving carriers are electrons.
Measure it. An ammeter reads current in amperes, and it belongs in series. A bad placement does not give a trustworthy reading.
Change one thing and predict. I = Q/t, and the rearrangements Q = It and t = Q/I. More time or more current collects more charge. Units have to match before the number means anything.
Estimate, not count dots. One electron carries 1.6 × 10⁻¹⁹ C. The swarm stands in for a huge number.
Hold two arrows. Conventional current is defined as the way positive charge would move, so in a metal it is opposite electron flow.

The last image is a question, not a certificate: you can see the flow, but what is pushing it? That is the door to potential difference. Coins and a small badge can appear. They are not the lesson.

Review against the node map

Mission 1 is complete for the locked scope: circuit, current, ammeter, I = Q/t and its rearrangements, electron charge, electron flow, conventional direction, one transfer, then the question that opens potential difference. It is not the whole electricity chapter. Resistance, Ohm’s law, combinations, and heating stay out.

The node map’s discovery line and its mastery graph disagree about electrons. The story sees them early. The graph unlocks the electron lab only after I = Q/t. The script keeps both: stage 2 is a look, stages 5 and 6 are the mastery. The early look does not count as M1-F or M1-G.

The graph asks for a formal “rate of charge flow” before the ammeter. That would put the sentence before the experiment. Stage 3 only establishes that the meter’s number is about the invisible flow. The rate becomes the sentence in stage 4, after the collector has been seen.

The draft never specifies the transfer scene, so a player could finish the workshop and miss M1-I. Stage 7 is that scene: Asha’s lamp, new circuit, new numbers, few hints. The clinic and the pump stay unsolved. Reaching the street is not mastery.

The official question-by-question CBSE audit is still not done. Nothing in this script is labeled a previous-year item.

Game script

Stages 0–8. Amp can nudge a part. Pico can pin a card. Neither of them teaches. If a student misses the same problem again and again, the third miss is an explanation. They still have to do the action.

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

Where: Ohm’s workshop. Wonder or Arav. Amp on the bench. Pico quiet.
Sees: One desk lamp. Rain. Dark village through the window. Cell, bulb, switch, cloth wires within reach. Leta’s clinic lantern is a small glow outside. The pump is silent.
Does: 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.
Works: Each part has been handled once. Their jobs are felt, not defined. No equation appears.
Fails: Nothing fails. Stalling is not an error.
Hint: If they touch nothing, Amp nudges the nearest untouched part.
Explains: 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.
Learns: A cell, a bulb, a switch, and wire are the pieces of this problem. Current is not named yet.

Stage 1 · M1-B

Make one light work

Where: Same bench. Circuit mat.
Sees: Ohm: “Make one light work. You have everything you need.”
Does: 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.
Works: The bulb glows amber. A short push-in, then a faint drift in the wire. Still unnamed.
Fails: 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.
Explains: 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.
Learns: A closed path lets something through. A break stops it.

Stage 2 · Look only · not M1-F

What is moving?

Where: Along the live wire.
Sees: Ohm: “Something is moving through the wire. What could it be?” A zoom lens.
Does: 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.
Works: They watch the carriers and can point the direction those spheres move.
Fails: 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.
Explains: 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.
Learns: 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.

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

The meter

Where: The bench. Ammeter is new.
Sees: Ohm sets the meter down: “If the flow is invisible, we need an instrument.”
Does: 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.
Works: A steady reading in A. The bulb still glows. The number is about the flow, not yet a lecture on charge per second.
Fails: 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.
Explains: 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.
Learns: An ammeter measures current, and it has to sit in series. A bad placement is a bad measurement, not a secret wrong answer.

Stage 4 · M1-E

Charge and time

Where: Current lab. Collector, clock, meter.
Sees: A current already on the meter. An empty glass jar that stands in for charge collecting. It is a model, not a school instrument. A clock. No formula on the wall. The ammeter is the real instrument.
Does: 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.
Works: At least two different setups are solved, including one rearrangement. The first prediction happens before any formula is shown.
Fails: 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.
Explains: 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.
Learns: 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.

Stage 5 · M1-F and M1-G

How many electrons?

Where: Same lab, microscope still available.
Sees: The charge just collected, chosen so it is a whole number of coulombs. The jar is only the picture of that charge. One electron is 1.6 × 10⁻¹⁹ C. One coulomb is the charge of nearly 6 × 10¹⁸ electrons. A swarm, not a pile of dots.
Does: 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.
Works: A reasonable estimate, and a clear identification: those moving charges are electrons.
Fails: 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.
Explains: 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.
Learns: The charge on one electron, and that metallic current is mostly those electrons. The direction clash is visible and not solved yet.

Stage 6 · M1-H

The arrows disagree

Where: A simple closed circuit and the evidence board.
Sees: Ohm: “You found the electrons. Now find out why our arrows disagree.” Two arrows: electron flow, and conventional current.
Does: 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.
Works: 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.
Fails: 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.
Explains: 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.
Learns: Conventional current is the direction positive charge would move. In metal, electrons go the other way. This is the assertion-reason moment.

Stage 7 · M1-I

Asha’s lamp

Where: The street. New circuit on the lamp post. Asha under it. Deepa has the access panel. Almost no Ohm.
Sees: A different layout from the bench: lamp, cell, switch, one loose cloth wire, a meter not yet in the loop. New numbers. The clinic is still on its lantern. The pump is still off. Bina is visible and has no quest.
Does: 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.
Works: That one street lamp blooms. Asha’s stall is lit. Nothing else in the village turns on.
Fails: 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.
Explains: 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.
Learns: The same rules hold on a different circuit. Reaching the street is not mastery.

Stage 8 · Story · not a puzzle

Cutscene · what is pushing it?

Where: The lit street. School, clinic, and pump still dark.
Sees: A short cutscene. Ohm does not say they have learned electric current. He asks: “Now that you can see the invisible flow, what do you think is pushing it?”
Does: Watch, or skip. There is no tool, no snap, and no right answer. Nothing the player does can solve it.
Works: 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.
Fails: There is no fail state.
Hint: None.
Explains: If they ask what pushes the charge, the cutscene does not explain potential difference. Ohm says that is the next investigation.
Learns: 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.

Plan

01CastdoneAmp, Pico, Wonder, Arav, Ohm, Leta, Asha, Bina, Deepa.
02Concept artdoneVillage, lab, props, electrons, rewards, key scenes.
03Visual identitydoneStyle, palette, camera, characters, world, UI and effects.
04Locked source rulesdoneExtracted from both Mission 1 PDFs. Not rewritten.
05What the game isdoneApproved. Investigation, not a lecture.
06Student takeawaydoneSix visual outcomes. The last beat is a question.
07Game script, stage by stagedoneHands approved. Stage 8 is a skippable cutscene. Fiddling is not a miss.
08Screen mockupsdoneStates show the gesture. Electron step is two dials, not a long crank.
09Source-to-gameplay mapdoneGrounded to the current section. Jar and swarm are models.
10Gameplay specdoneGenerous snaps, committed tries only, cutscene does not wait.
11Developer handoffdoneSyllabus boundary, systems, metadata, events, access, assets, acceptance.
12Illustrated websitedoneFinal PRD. This site. Electron Dodger is optional. Everything else is core.

Locked from the source PDFs

These rules stay even if screens change. Chain: source, concept, outcome, atomic skill, player action, mechanic, feedback, assessment, mastery, story.

Gate	Skill	Needs	Evidence	Opens
M1-A	Components	None	Identify and inspect parts	Circuit builder
M1-B	Closed circuit	M1-A	Build a working circuit	Current lab
M1-C	Current	M1-B	Explain rate of charge flow	Ammeter
M1-D	Ammeter	M1-C	Place and read it	Charge collector
M1-E	I = Q/t	M1-D	Solve more than one variable set	Electron lab
M1-F	Electron charge	M1-E	Estimate count with 1.6 × 10⁻¹⁹ C	Direction mystery
M1-G	Electron flow	M1-F	Name the carriers in metal	Direction mystery
M1-H	Conventional current	M1-G	Place the conventional arrow	Final investigation
M1-I	Transfer	M1-H	New situation, few hints	Mission 2 hook

Do not turn every idea into an MCQ.
Do not show the formula before the experiment.
Do not click Next through a lecture.
Do not mark a wrong move with a red X.
Do not bury the science in story.
Do not lock required science behind coins.
Do not call an item a CBSE question unless the source metadata is verified.
Do not treat previous-year papers as a separate quiz room.
Do not paste copyrighted question text into the game. Rewrite the scenario.
Do not call the mission mastered because the player reached the last room.

Feedback order is consequence, then hint, then explanation. Partial reasoning can move the scene forward. Mastery still needs the full evidence chain, including one transfer with little help. The question audit against official CBSE papers is still a separate task and is not claimed as finished.