Space Quest 2 Playthrough Analysis

This chapter records a game-specific, clean-room reconstruction of a maximum- score winning playthrough for the local SQ2 evidence set. It is intended to become a repeatable conformance scenario, not part of the portable AGI engine specification. The route was derived from canonical logic, vocabulary, object, picture, and view resources without consulting an external walkthrough.

The result is currently a static candidate route. Logic control flow, messages, parser vocabulary, inventory mutations, and score mutations support the story and puzzle sequence. Exact movement keystrokes, moving-hazard timing, and score checkpoints still require replay under the original interpreter.

Evidence Method

The reusable playthrough index can be generated with:

AGI_GAME_DIR=games/SQ2 \
  python3 -B tools/logic_playthrough_index.py \
  --output build/playthrough/sq2/index.json

The index contains 118 readable logic resources, 2,472 parser conditions, 182 room transitions, 70 score mutations, and 40 inventory slots. Directory entry 141 points at VOL.0:0x1ffff, which does not contain a valid resource header; the index records it as unreadable and continues with valid resources.

Logic 104 assigns 250 as the declared maximum score. All positive score sites sum to 283. The excess consists of alternate parser branches and puzzle solutions rather than 283 points available on one designed path.

A direct renderer sweep produced all 74 valid picture resources. The resulting contact sheet corroborates the forest, swamp, cave, shuttle, asteroid corridor, Vohaul machinery, ruptured tube, pod-bank, and escape-pod progression described below. Picture-directory entry 147 points at VOL.0:0x2ffff, where no valid resource header exists; like unreadable logic 141, it is preserved as directory evidence rather than interpreted as game content. Pictures 140 through 146 are title or interface imagery rather than additional traversable rooms.

Story State Model

The winning route has three large phases:

1. Work aboard Xenon Orbital Station 4, then be abducted and sent to Labion.
2. Escape Labion and take a shuttle to Sludge Vohaul’s asteroid.
3. Infiltrate the asteroid, stop the salesman-clone launch, escape its orbital destruction, and enter suspended animation.

The terminal winning state is reached in logic 93 after entering the escape pod’s sleep chamber. Its messages state that Vohaul and the clone plan were defeated, display the closing title, and leave the player in suspended animation. The conformance scenario must reach this state with score 250.

Candidate Route

Orbital station and abduction

1. While working outside XOS 4, answer the wristwatch call by pressing its C control. This optional response awards one point.
2. Step onto the airlock platform when ordered inside. Completing the transfer into the airlock awards one point.
3. Change from the EVA suit into the station uniform at the suit rack. This awards one point and retains the order form and dialect translator.
4. Open Roger’s locker and take both the athletic supporter and Cubix Rube puzzle. Each is a separately guarded one-point acquisition.
5. Travel through station control to the shuttle bay and enter the shuttle. The abduction sequence awards five points and eventually deposits the captive player on Labion.

End-of-phase score: 10.

Labion forest and swamp

1. After the hovercraft crash, press the flashing, beeping button in the wreck to switch off its locator for one point. Search the dead guard and take the keycard for three points.
2. Find the small pink being caught in a snare and free it by releasing the rope. Its escape awards five points and establishes the later cliff-dweller welcome state.
3. In the spore clearing, take one live spore for four points. The two four- point sites are alternate near/far acquisition branches guarded by the same state, not cumulative awards.
4. Put the order form into the clearing’s mailbox for two points. Return after its delivery cycle and take the whistle from the tray for another two.
5. Survive the root-monster area and take the red berries for two separate four-point awards: one for completing the encounter and one for acquiring the berries. Rub the berries over Roger’s body for three points. Their odor is used to avoid detection by the searching hovercraft; completing that evasion awards five points.
6. At the swamp, take a deep breath before diving. The first valid breath/dive state awards two points. Reach the underwater grotto for two points, take another breath there for two, and take the glowing gem for three. This is the higher-valued gem acquisition; do not later take the one-point fallback gem in the cliff-dweller cave.
7. Allow the forest hunter sequence to capture Roger and place him in the cage. Throw the live spore at the hunter from the proper position to paralyze him for five points. Take the cage key for two, unlock and open the cage, then take the rope for two.
8. Return to the fissure. Climb the dead snag for three points, then tie the rope to either the stump or the log for two. The two anchor awards are alternatives; untying the rope removes two points.
9. Descend the fissure and swing on the rope. Initiating the useful swing awards two points. Release at the correct part of the arc to reach the ledge, awarding five points.
10. The cliff dwellers recognize the earlier rescue. Follow them through their cave and, when their leader offers to reveal the exit, say the word. This awards three points and opens the descending route.
11. In the dark tunnels, hold the glowing gem in Roger’s mouth so he can crawl while retaining light. Successfully reaching the luminous underground water awards 20 points.
12. Follow the river and survive the forced whirlpool sequence. Reaching the waterfall pool outside awards five points.
13. In the terror-beast clearing, blow the mail-order whistle to summon the beast for five points. Give it the Cubix Rube for ten; while it is occupied by the puzzle, take the small stone from the newly created debris for two. The two stone pickup sites describe the same inventory acquisition.
14. At the landing platform, use the athletic supporter as a sling and fire the stone at the guard while outside his direct line of sight. The successful hit awards 20 points. The two ten-point bush-distraction branches are lower-valued alternatives and consume the same stone.
15. Search the unconscious guard and take his keycard for one point. Insert it into the elevator slot for five.
16. In the shuttle, power the ascent system, select vertical attitude control, activate the ascent thrusters, and use the throttle as indicated by the console. Achieving the required altitude and departure sequence awards 20 points. Vohaul then takes remote control and brings the shuttle to his asteroid.

Labion contributes 156 points. Cumulative score: 166.

Vohaul’s asteroid

1. Explore the asteroid’s elevator levels before committing to the final security route. Collect the following janitorial and utility items:

   • Plunger from the dark closet in room 62: one point.
   • Glass cutter from the dark closet in room 72: one point.
   • Toilet paper from the human restroom in room 76: one point.
   • Wastebasket and lighter from the holding-level closet in room 83: one point each. Inspecting or taking the dirty overalls exposes the lighter.

2. Put the toilet paper into the wastebasket for one point. Preserve the resulting basket-with-paper for the Wallbot corridor.

3. Enter the moving-floor acid trap in room 66. Completing its first barrier sequence awards ten points. At the smooth barrier, attach the plunger and hang from it while the floor retracts; the successful plunger state awards another ten. Do not release early.

4. In the Wallbot corridor, put down the loaded wastebasket in the accepted position for one point and ignite it with the lighter. The heat triggers the sprinklers; the water extinguishes the fire and shorts the Wallbots. The successful sequence awards ten points.

5. Enter Vohaul’s control chamber. The miniaturization beam traps Roger in a glass jar on the console. Use the glass cutter to cut an exit and complete the miniature escape sequence for five points.

6. Enter the console vent, reach Vohaul’s life-support machinery, and press the emergency shutoff. Disconnecting his life support awards ten points. Return to the console and use the beam sequence to regain normal size.

7. Examine Vohaul’s hand to learn the written code SHSR. Use the control console and enter SHSR to abort the salesman-clone launch for ten points. This action starts the asteroid’s terminal orbital-decay phase.

8. Open the wall receptacle in the clear outer passage and take the oxygen mask for two points. Wear it before traversing any ruptured, depressurized tube.

9. Return to the escape-pod bank while avoiding the Marrow-Matic and other moving hazards. Enter the available pod for ten points and launch before the asteroid is destroyed.

10. After launch, the pod reports rapidly dwindling oxygen. Open the sleep chamber and enter it. Sealing the chamber awards the final ten points and enters terminal logic 93.

The asteroid contributes 84 points. Final score: 250.

Score Ledger

The complete positive-site sum is 283. The designed route removes 33 points:

Thus 283 - 33 = 250. No negative score action is needed. Avoid changing back into the EVA suit, untying the rope after scoring an anchor, and trying to retrieve the suspended wastebasket from an invalid position.

Deaths and Dead Ends

The logic resources expose many useful negative conformance cases:

• Step off the orbital-station structure and drift into space.
• Leave the airlock without the EVA suit.
• Enter concealed forest spike pits or touch sticky/insect-covered trees.
• Approach the root monster incorrectly or fail to escape its digestive path.
• Enter deep swamp water without taking a breath or remain submerged too long.
• Let the hunter recover before escaping the cage.
• Fall from the fissure, mistime the rope release, or enter dark caves without the gem.
• Meet the cliff dwellers without having rescued their companion.
• Enter the cave-squid tunnel without enough light or take the fatal river branch.
• Approach the terror beast without distracting it.
• Let the platform guard see Roger while attacking or following him.
• Fall from asteroid walkways or enter vacuum without the oxygen mask.
• Release the plunger during the acid-floor trap.
• Approach active Wallbots, Marrow-Matics, floor waxers, or caged creatures.
• Fail to stop the clone launch or remain on the asteroid during orbital decay.
• Set the miniaturization beam incorrectly, remain trapped without air, or fail to disable Vohaul’s life support.
• Launch successfully but fail to enter suspended animation before the pod’s oxygen is exhausted.

Potential progression dead ends include discarding the puzzle, supporter, whistle, gem, keycards, plunger, glass cutter, lighter, paper, or wastebasket before its final use. A conformance suite should distinguish these valid but unwinnable states from immediate death states.

Next Validation Work

1. Convert each milestone into exact movement and parser input under QEMU.
2. Record room, inventory, and score checkpoints at 10, 166, and 250.
3. Confirm moving-hazard timing, patrol evasion, rope release, acid-floor survival, and Wallbot placement under the original interpreter.
4. Package the validated input stream, screenshots, and terminal assertions as a repeatable implementation-conformance playthrough.