Portal/Speedrunning

Wikipedia defines a speedrun as "... a play-through (or a recording thereof) of a video game performed with the intent of completing it as fast as possible". The article goes on to discuss the use of cheats and "glitches", playing in a single "segment" or pasting together the best of multiple attempts in separate segments and other variations of speedrunning. We see that there are many ways to speedrun a game, each with its own set of rules that define what is allowed and what is not allowed.

Fastest Speedruns
The fastest times are achieved by highly skilled players working together to complete small segments of the game individually. The best time from all the players working on each segment will be pasted into the video of the final run. The players will exploit defects in the game engine or level construction ("glitches") and execute maneuvers that most players would find impossible. Those players are unlikely to be looking at strategywiki, however.

No Cheating SpeedRun in One Segment for Mere Mortals
If you've completed Portal, with or without help from these pages, and have made some progress on the time challenges of Chambers 13 to 18, you just might enjoy trying a speedrun. Here is a suggested set of rules for you to follow. On the individual Chamber pages there is a section explaining how to apply these rules to that chamber, where you can study them in the context of the normal chamber solutions. To see if you are ready for this speedrun, simply sit down when you have an uninterrupted hour or two and play the game through from beginning to end. If this takes you an hour or less, you are ready. If it takes you much more than an hour, by all means have a go, but you might find it frustrating if, for example, you try something risky and die two-thirds of the way through. The suggestions given here (on the individual Chamber pages), when properly executed, should give you a speedrun time down around 30 minutes.

No Cheating
Some glitch exploits are easy (such as portal bumping) and others are more difficult (such as accelerated back hopping). The easiest thing to do to level the playing field for most players is to classify all exploits as cheating and ban their use. This does, of course, raise the question of what is a glitch exploit and what is a reasonable part of the game mechanics. A simple rule of thumb is to consider whether something is consistent with the universe of the game. The Portal universe is similar to our own universe except that there exists the portal gun and immunity from long-fall damage. "Peek-a-Portal" and "Portal Standing" are consistent with that universe because they are a reasonable consequence of the existence of portals. Throwing a cube is reasonable even in our universe. So, these are all considered valid gameplay and not cheats. Accelerated back hopping, however, exploits the fact that the game engine designers stupidly decided to slow you down when you land from a jump by giving you a short push backwards. So, jumping when you're already going backwards results in you going faster each time you land. This is not justified by the portal universe; it is taking advantage of (exploiting) a mistake. So, it is cheating and not permissible under these rules. There will be borderline things that are subject to debate. If you want to compare your time with other people, check the rules that they are following. On the other hand, of course, the most important thing is to have fun.

One Segment
The most straightforward way to speedrun is from the start of the game to the end using an ordinary clock or stopwatch to measure your time. This is called a single segment speedrun. The advantage of this is that you don't need to record and edit a video or use other tricks to account for time. The disadvantage is that you have to stand helpless during some boring parts where GLaDOS is delivering a speech or some other timed action is taking place or the next level is loading and the clock is nevertheless ticking. The widely accepted definitions of the start and end of the game are the appearance of the aiming crosshairs soon after you stand up in the relaxation vault, and their disappearance soon after you dump the last core into the incinerator. Some players subtract level load times or other periods in order to reduce their speedrun time. Again, if you compare your time with other people, make sure they are following the same rules that you are.

Mere Mortals
The speedrun described here does not require feats of extraordinary skill. The skills that you will need are described on the tips and advanced techniques page. If you don't possess these skills, you can still try the run, but your time will not be so good. These are some of the skills that will come in useful:
 * Maneuvering in mid-air (Chamber 14 and Chamber 15)
 * Peek-a-Portal (Chamber 15 and Chamber 19)
 * Portal Standing (Escape 00)
 * Cube Throwing (optional in Chamber 05)

However, you do need to be able to execute normal moves with confidence and precision and without hesitation. You must memorize the game and the route that you develop to get you through it. As you move into each new area or come out of each portal fling, you must know which way to turn and what to do next to keep yourself relentlessly moving forward. You will not get a good time if you frequently need to stop and look around to bring to mind where you are and what's next.