Surely it takes more than a good story holding everything together to make something an adventure game?
Most try to define adventure games by examining their game play mechanics, I think. Certainly when I hear the term I imagine point-and-click games such as those created by Sierra and LucasArts (and their text-based predecessors). Mechanically, those games have very little in common with Portal.
I would define an adventure game as a game that delivers a narrative that is unlocked primarily via exploration and puzzle solving. Adventure games may have elements of other genres incorporated into them, but those elements should not be the main focus of the game, and should (generally) only be employed as part of a puzzle process. Solving a particular puzzle might, for example, involve a minigame in which the character must play a combat-oriented video game within the game to obtain a piece of information (someone’s initials on the high-score table, say).
This is distinct from action games, which unlock narrative mainly through exploration and combat. I classify platformers as a subset of this. (I think of platforming as the extreme sports version of exploration.)
Portal is an edge case. Its primary mechanism is puzzle-solving, but platforming plays a substantial role in solving the puzzles. There is only one combat…and it’s effectively a minigame with both puzzle and platform elements, more than a traditional combat.
I’d call it an action-adventure game–a very common hybrid–and give the argument a rest. 
I’m glad I’m not the only one! It really wasn’t THAT difficult - the only thing you needed to change to switch this puzzle from “stupidly annoying” to “tricky but well done” would have been to change it so that the vending machine was willing to dispense an infinite number of fishes, rather than the three or whatever it was willing to do in the game. (Net result: You saved right before starting the puzzle, which was bloody well near the beginning of the game anyway, then restarted whenever the machine ran out of fish.) From there it’s a fairly simple matter to use your bewildering array of like, 4 items to solve the puzzle.
That said, yeah, HHGTG was pretty much a sendup of the idiocy that happened in some of these games. I never got anywhere near to finishing it, but I enjoyed it quite a lot because it seemed like such an effective translation of the source material.
THAT said, I’m pretty firmly in the “adventure games comitted suicide with their stupid puzzle logic” category. Though I suspect very strongly that this was ALSO one of our first experiences with the issue we see so much of today: Namely, rising development costs for big retail titles causing niche genres to be unable to sustain themselves in that space. Even with the same number of people buying them, or even a slowly increasing number of people buying them, as adventure games went from “a couple of guys coding in their basement” to “a full team of programmers, artists, voice actors and composers”, it’s hard to believe that they could maintain profitability. Essentially, the standards for what people “expected” of a game increased (VGA art! Full midi soundtracks! Voice acting!) a lot more time and therefore money had to get put into them, and there just weren’t enough people buying them to sustain that. It’s the same reason that there basically aren’t any (or at least very few) AAA games in “niche” genres today. Each of the prodominant “niche” genres has, at best, one flagship title every few years. 4X has Civ and…Civ. RTS is basically JUST Starcraft 2 at this point… and I guess the Total War series, which also comprises pretty much the only AAA “strategy” game. Other, even more nichey genres don’t exist in the AAA space at all because they don’t sell enough to support the costs, so you see them as budget games or indie stuff. Which coincidentally is where all the adventure games are now. Coincidence? I rather doubt it.
I disagree. I don’t see what inherently links puzzles to adventure.
I know there was the game Adventure, so it could be the word means similar to that, but I think it’s misleading terminology in that case, because in general parlance people associate action with adventure.
The connection arises from the fact that the genre was actually named for the game Adventure. The “adventure” in “adventure games” was originally a proper noun, and part of how players described the games to others. It was shorthand for “a game in the same style as Colossal Cave Adventure”. Games of another genre that arose around the same time are called “roguelikes” for the same reason. They do not wink or try to steal your stuff (well, not usually), they offer the same type of gameplay as Rogue: a D&D-based ASCII dungeon-crawl RPG.
In a sense, this naming convention itself supports Lowe’s contention a bit. It reflects a pattern in the thought processes of those who played computer games back in the days when filenames were limited to six characters and communication was often more terse than modern textspeak due to technical limitations. Among the community that talked about games, familiarity with the primal games was assumed, and communication relied heavily on references.