Small World was written in TADS and is © 1996, 1998 by Andrew D. Portius.
This solution is by David Welbourn, and is based on Release 3 of the game. (Are you sure you need a walkthrough? This game does have in-game hints, after all.)
A few opening remarks. First, several standard verbs have been disabled for this game, including ask, attack, break, climb, dig, hit, listen, kill, pull, and search. Second, examining any article of clothing will trigger an automatic disrobing of the article first, which frankly I found rather annoying. Third, in keeping with the theme of a "small world", awarded points are fractional. A full score is 1 point.
Map 1: The Surface of Small World
Look at your stuff...
>x me. i. x backpack. open backpack. x glass.
>x pants. (+.02pt) x boots. x socks. wear pants. wear socks. wear boots.
>x canteen. open it. x gatorade. drink it. (+.01pt)
...and look at your surroundings...
>look. x key. turn key. x panels.
>x midnight. x evening. x twilight. x afternoon.
>x noon. x morning. x dawn. x gloaming.
...and go south. Well, one of the souths.
Be good to the lagoon. Take some excess clean water, but leave the remaining water, and don't pollute any of it.
>x sea. smell sea. x lagoon. fill canteen with lagoon. (+.03pt)
Learning how to use the magnifying glass:
>x jungle. look at jungle through glass.
>look at civilization through glass. m civilization.
(You can also examine/magnify the canoes. All the "civilization" objects in the game may be ignored, or be examined several times with the magnifying glass.)
>x commotion. m commotion. (+.02pt)
>x ocean. west.
>x satellite. take it. (+.01pt)
>x missiles. x lights. m lights.
>x signs. m signs. x mountains. x tallest mountain.
>x ice cream. take ice cream. take ice cream with spoon. (+.03pt; Don't eat the ice cream! It'll kill you!)
>x men. m men. x volcano. (A devil appears!)
>x devil. x wand. read runes. x parchment. read parchment.
Don't sign the contract. Just don't. Bad idea. Until you sign the contract, or deal with the devil some other way, he's going to follow you around. Actually, you can deal with the devil right now, but let him stay for a bit to see how he uses his wand.
>x fire. m fire. x moon. touch it. take it.
>x wormhole. touch it. put moon in hole.
Anything put into the wormhole is lost for good. But at least dunking the moon in it is fun. By now, you've probably seen the devil wave and point his wand, so you can get rid of him.
>give ice cream to devil. (+.05pt; bye-bye devil!)
>take wand. (+.02pt) read it. take contract. read it.
>m hell. x devil.
You may have noticed fleeting images of trios of numbers in various locations. None of these mirages are the true combination to this door.
>x door. x lock. west.
Careful. You can't go up to the sun until the dust settles somewhat. The dust won't settle until the riverbeds are refilled. You can't find the riverbeds while wearing boots. You will die (via sandworm bite) if you're here in your bare feet. So, you can only find the riverbeds while wearing socks without boots. Unfortunately, your socks will get sandy, but more about that in a bit.
>x dust. x riverbeds. touch riverbeds.
>take boots. x riverbeds. touch riverbeds.
>pour water on riverbeds. (+.05pt)
>x dust. x riverbeds. touch riverbeds. x men. m men.
>x sun. (Don't go up to the sun yet; you need to get your boots back on, and you can't go that with no socks or sandy socks.)
>x traces. m traces. x stars. (+.01pt; Remember the word you saw! It's different each game.)
|s↓↑u||*walk on ring|
Map 2: Small Solar System
>wash socks. (+.02pt) wear socks. wear boots.
>s. noon. up. (+.10pt)
Don't go to the green planet or the gas giant just yet. The people on the green planet can entrap you, and you can drown in the gases of the gas giant.
>x small world. x green planet.
>x odd-looking moon. take it. read it.
>x gas giant. x ring planet.
>x rings. x ring. x sun. up. (walk on rings. undo.)
>walk on ring.
The ring may have fallen anywhere on Small World. If it's not here, go look for it, pick it up, and come back here. Assuming it is here:
>take ring. (+.04pt) x it. wear ring. (+.02pt)
The ring is keeping you afloat and alive here, so don't take it off!
>x gases. smell gases. x core.
The next part is time-critical.
>inhale gases. (+.04pt)
[Small Green Planet]
>exhale gases. (+.05pt)
>x green men. m green men. x clothes.
>look. x chest. read it. open it. x baubles.
>wave wand. point wand at chest. (+.05pt)
>take wand. take baubles.
Most of these treasures are injokes. Only the magic pipe will prove to be of any use.
>x lightsaber. x stud. push it. (kudos to Star Wars)
>x painting. (kudos to Heist)
>x declaration. read it.
>x urn. read it.
>x pipe. x buttons. x ends. read pipe.
>x stiletto. (kudos to Zork I)
>x rod. wave rod. (kudos to Sins Against Mimesis)
>x roadrunner. (kudos to Trinity)
>up. n. n. dawn.
>m commotion. (+.10pt)
>x heaven. m heaven. m pete. m express.
>say "[word-seen-at-South-Pole]". (+.05pt; Remember the numbers that Pete tells you! They're different in each game.)
>e. e. e.
>turn dial to [first-number-that-Pete-told-you].
>turn dial to [second-number-that-Pete-told-you].
>turn dial to [third-number-that-Pete-told-you]. (+.05pt)
>open door. x hole. down.
Map 3: Inside
[Hole in the World]
>look. x motor. x upper pipe. x lower pipe.
>connect magic pipe to upper pipe. connect other end to upper pipe.
Hmm. Time to figure out what how the magic pipe works.
Pushing the solid button transforms the pipe's shape, cycling through the following shapes in this order: straight, V, square, U, S, straight, sine, circle, triangle, steps, boomerang, sine, straight (as at the beginning).
Pushing the swirled button changes the color of either the "one end" or the "other end" of the magic pipe, cycling through the colors in this order: red, purple, brown, silver, gold, yellow, white, pink, aqua, sky, forest, orange, red (again).
Hopefully, it's obvious that you want to put the magic pipe straight between the upper and lower pipes, changing the colors on the ends of the magic pipe to match the upper and lower pipes as well.
The trick is to notice that pushing the swirled button will alternate between the two ends of the pipe as long as the shape isn't changed. But whenever the shape changes, the next push of the swirled button will change the "one end", not the "other end", first.
So... the first step is to set the color of the "other end" to either silver or sky blue.
>push swirled button. (Repeat push swirled button until the "other end" is either silver or sky blue.)
The second step is to set the color of the "one end" to either silver or sky blue, whichever the "other end" isn't.
>push solid button. push swirled button. (Repeat pushing the buttons, alternating between them, until the "one end" is the desired color. The color of the "other end" shouldn't change.)
The third step is to change the shape of the pipe to something that will fit onto one of the room's pipes, without dislodging during an attempt to straighten the pipe again. This means you want to cycle the pipe to the sine shape that's immediately before a straight shape.
>push solid button. (Repeat pushing the solid button until boomerang, then push it once more for the sine shape.)
Assuming the "other end" is silver, connect it to the lower pipe (else if it's sky, connect the "other end" to the upper pipe).
>connect other end to lower pipe.
>push solid button. (+.10pt)
>turn key. (+.10pt; you win!)