Speedrunning of video games is a very interesting hobby to follow. Unassisted speedruns are often real shows of skill and expertise, and it can be real fun to watch a difficult game being completed in one tenth of the time (or even less) than a normal first-time playthrough, especially when doing so involves really skillful maneuvers that are very hard to pull off and require tons and tons of practice. It could perhaps be slightly compared to a skillful juggler, or parkour. Tool-assisted speedruns are interesting to watch because they depict, essentially, what it would look like if a superhuman perfect player played the game: A perfect playthrough as fast as possible with zero mistakes or inefficiencies.
In both cases there's an important key concept involved: Playthrough. As in playing the game from beginning to end. Playing the game from beginning to end.
Then they started discovering bugs, defects and glitches in various games that allowed them to skip parts, sometimes even large parts, of the game. Such glitches are often interesting (and sometimes really hard to pull off, which adds to the skill level), but as long as it happens purely through gameplay alone, it's fine. (Sometimes they skip large parts that would have been nice to see played through, which is a pity. Sometimes they make a longer and more boring run shorter and more interesting, so the overall entertainment value increases. It depends a lot on the game and the glitches in question.)
Then they start discovering glitches that do not involve actual gameplay (in other words, feeding input to the game itself that it uses to control the gameplay, eg. the movement of the playable character, etc.)
Like "if I quick-save and quick-load repeatedly here, it allows me to glitch through this wall" (as is a relatively recent trick in Half-Life 2 speedruns.) I suppose it's debatable whether quick-saving and quick-loading is part of actual gameplay. In my opinion, it's not. (Sure, they are necessary to resume the game if the player dies, but I still don't consider them part of actual gameplay. They are a mechanism external to the gameplay itself, and not part of actually playing the game.) This could be considered a borderline case, but personally I don't consider it legit gameplay, and thus I really don't like it. (Additionally, I find it quite egregious that runners are still calling those runs "single-segment" when they are quick-saving and loading dozens of times. That's not single-segment. But that's besides the point here.)
Then they discover glitches like "if I quick-save, then go to the game's main menu and delete the save from there, and then resume, it allows me to skip this part". Going to the main menu and deleting a save file is most definitely not part of the gameplay proper in any way, shape or form. This is inducing a glitch into the game via external non-gameplay methods. This is not playing the game anymore. (If the argument is that it all happens from within the game, using the tools that the game itself offers, then by the same argument you could simply open the console and start writing cheat codes there. Games like Half-Life 2 support this, fully within the game, using tools that the game itself offers. No, just no.)
Then they discover glitches like "if at this point I alt-tab to the desktop, start the task manager and kill the game from there, and then restart it, it allows me to skip this/duplicate items/whatever" (like with games like Minecraft). Likewise in some consoles "if I reset the console at this point, it corrupts the savegame." No. A million times no. This is not playing the game by any possible definition of the concept. This is not "speedrunning" anymore. This is not completing the game via gameplay. It's corrupting the game via external means, and is no different from simply using cheat codes, hex-editing the savefile or modding the game.
Yet, year by year, more and more of these non-gameplay tricks are being discovered and classified as a "legit" way of speedrunning the game. Speedrunning is going farther and farther away from actually playing the games. Some of those tricks may be interesting for the sake of curiosity, but they are killing what makes speedrunning so exciting and marvelous.
With some games this is going into another tangent: While technically speaking the glitching is done via gameplay (ie. solely by the input keys that the game interprets as controls for gameplay), the glitches nevertheless are such that they alter the game code itself and allow for arbitrary jumps anywhere within the game's code. The most prominent example of this are the first-generation Pokemon games.
For a long time there was a way to glitch the games to jump to any arbitrary location, but this glitch involved resetting the game while it was saving. Recently it was discovered that it can be done without resetting, purely via the normal gameplay buttons (ie. directional buttons and the A and B buttons). Essentially what happens with this glitch is that at some point the game is tricked into loading the wrong room when the player goes through a door, and this wrong room is the Hall of Fame room (which for the intents of speedrunning is considered the game's ending.) This is nice and interesting... but it still leaves a bit of a bad taste in by mouth, because the game wasn't actually played through. The game was corrupted in such a way that it loaded the wrong room and thus the run jumped to the end without actually playing the game.
To understand my problem with it better, consider that if there was a way to do that from the main menu of the game right from the start (or the very first room where you start in), they would do that. They would jump directly from the very beginning of the game to the very end... and that's it. That's somehow a "speedrun", ie. completing the game as fast as possible... without actually playing the game or completing anything. And this isn't like the ending is right next room and you glitch through the wall due to a bug or bad level design; this is done by corrupting the game and making it jump to a completely different routine than normally. Even if the corruption was caused by using the input keys alone, the game was not played through. (Again, this also could be considered a borderline case, but personally I just don't like it. I don't consider this speedrunning. It's not playing the game.)
Tool-assisted speedrunning isn't free from this either. On the contrary, it's even worse (because it's far more frequent.) For something like 10 years tool-assisted speedruns always completed the game "cleanly". Sure, with some games lots of glitches were abused, like zipping through walls and so on, but nevertheless the games were played from beginning to end, through each level that had to be played at minimum, starting from the beginning of the level and progressing to the end, and so on. Some local level-abuse aside (which is fine in my books), this was pure and clean gameplay, from beginning to end, as fast as possible.
Then they started discovering that hey, if we abuse the reset button, we can corrupt the game's savedata, or corrupt the game in other ways. Emulators didn't support recording the reset button, so this technique was unusable in practice. Then they added support, and dozens of speedruns were immediately ruined by it. Resetting the game is not gameplay. Corrupting the game's savedata via resetting is an external, non-gameplay technique. It's not a legit completion of the game in my books.
A few years later people started discovering a different trick in some games: They could glitch the game into executing arbitrary machine code, which could be inputted by the runner using the controller. This is a very nice and interesting technique in itself, and allows for some quite spectacular results (such as making a game run a completely different game that was inputted to it via the controller). However, in terms of speedrunning... well, it isn't anymore. Once you have taken control of the console and are able to input and execute whatever machine code you want, you have stopped playing the game. The actual "speedrun" is over. This is not gameplay anymore. You have simply hacked the game and took control of the console, and can now program it to do whatever you want (within the limitations of its RAM capacity.) Thus anything you do from this point forward is not a speedrun of the original game anymore. It's over. Moreover, you didn't even complete the game, and thus it's not a full, legit speedrun of it.
But of course they consider it a "legit" speedrun of it. After all, one of the things you can do by executing arbitrary code is to jump to any routine within the game's own code (and set any RAM values you want, if needed). Pick an arbitrary point in the game that you consider its "ending", and jump there. Done, game completed? And most of the games glitchable in this manner have a published "legit" tool-assisted speedrun that does exactly that.
No, just no. The gameplay ended immediately when you hacked the game and took over the console. You are not playing the game anymore. The run is over. Anything else you do after that is not a legit speedrun. It's executing your own code. Just because you can now jump to any arbitrary routine within the original game program doesn't somehow return it to be a legit speedrun of the game. You did not complete the game via gameplay.
I find it really sad that this is becoming more and more common, both in unassisted and in tool-assisted speedruns. Especially in the latter case the non-speedrun is sometimes even considered the only official fastest completion of the game, replacing any non-glitched speedrun of it. In other words, for some games there exists no current official tool-assisted speedrun of it (not in my books at least.) If you want to see an actual speedrun, you'll have to find an older version.
I think this is ruining speedrunning in the case with many games (where these non-gameplay tricks have been discovered). Lost are the days when these games were actually played through as fast as possible. Now they are just corrupted and glitched using external means or, in a few cases, by arbitrary code execution (which is not gameplay in my books.) Moreover, in many cases runs using these tricks are often considered the only current "world record", so you essentially get no choice (other than be content with older, perhaps obsolete versions.)
Of course speedrunners are completely free to do whatever they want, and consider whichever run they want to be "legit". I just think it's a pity that these non-speedruns are becoming more and more common, ruining the whole concept. (Fortunately these tricks can, so far, be used in only a minority of games, which saves the day for me. Unfortunately the tricks are being discovered in some of my all-time favorite games, like the Half-Life series, which just ruins it.)