+=3

This game makes a point about interactive fiction design. It makes it well and quickly (one you have figured out the solution, probably by reading the source or the walkthrough). So, although this game is not enjoyable as such, it does the one thing that it attempts to do quite well.

What is the point that it makes? According to Karl Muckenhoupt, the point is that "it is possible for a puzzle to have a completely logical solution, and yet be nearly impossible to solve except by randomly guessing commands". Without disagreeing with that, I would say that the point of +=3 is that "conventions of play are there for a reason". Either way, it's a good point, and +=3 is a name that you might want to drop in a discussion now and then.

+=3 was intended to make the point that a puzzle can have a perfectly logical solution and still be virtually unsolvable.

it does not make this point, as the puzzle does not have a logical solution.

for those not in the know, the goal of the game is to pay a troll by handing it three items. this is the first puzzle and the only puzzle, and you encounter it immediately. however, there aren't three items in your inventory, nor are there any other items to be picked up. so, what to do?

the solution presented is to (Spoiler - click to show)think of objects that have been implemented but that are never mentioned in any descriptions at all, that are omitted from your inventory even though you possess them, and that can't be found by examining yourself -- specifically, clothes.

unfortunately, as too often happens when an author is trying to lecture the audience, it just doesn't hold up.

first, regarding the response to EXAMINE ME. (Spoiler - click to show)you're described as the adventurer from Zork. there was an object that said adventurer possessed that wasn't implemented -- the compass, mentioned only in the Alice-in-Wonderland area in Zork II. but it couldn't referred to. this conveys the information that you're a fantasy adventurer -- yet the words BOOTS and ARMOR aren't implemented. thus, even if someone does think of trying to obtain items by undressing, the first words they're likely to try won't work, and they'll give up on the idea!

second, regarding the game's tiny nature. (Spoiler - click to show)you're said to have just conquered a dungeon, but the game won't let you retreat to gather more items. in the games of this era there was always detritus left over -- the adventurer from Zork would at least have a lamp and sword. there's no logical reason to block this area off; the game is just refusing to allow you to go there because it isn't the intended solution.

and lastly, regarding the shallow implementation. (Spoiler - click to show)a handful of different words for specific articles of clothing -- modern ones -- are available. given the esoteric nature of the solution, again, someone isn't necessarily likely to keep trying clothing nouns unless they happen to hit on one first try. trying to remove my dress or shoes and being told the game doesn't understand would cause me to discard this way of thinking. this game needed a LARGE vocabulary of garments -- and given how little game there is otherwise, there was absolutely time to implement it.

overall, the reason that this puzzle is "logical but impossible" is because the author's rigged things up that way. all this proves is that IF authors are able to write puzzles where the only way most people can proceed is to read the author's mind or guess the right word, and buddy, that ain't news.

This is a troll game in multiple ways. First of all, there is a troll. The point of the game is to cross the bridge that he is guarding.

Second, it's designed to have a ton of red herrings, like an overly-complicated calculator and a recurring noise.

Third, the whole point of the game is to prove a point in an argument.

The main argument is whether a logical solution is a solvable solution (and the point here is that the answer is 'no').

This remains a big sticking point in parser design three decades later. Many authors are surprised to find players getting stuck in parts of the game that should be logically clear or blindingly obvious; a lot of this is because for most parser games there are many logical things that we politely ignore, like realistic carrying capacities or getting tired or using the restroom. Those things are ignored because, when implemented, they are generally dull and boring. The experience of playing is, to me, more important than realism, and that ties back into this game's themes; while the game is logical, it not an enjoyable experience.