Editing Tool-assisted speedrun (section)

==Method==
Creating a tool-assisted speedrun is the process of finding the optimal set of inputs to fulfill a given criterion&nbsp;— usually completing a game as fast as possible. No limits are imposed on the tools used for this search, but the result has to be a set of timed key-presses that, when played back on the actual console, achieves the target criterion. The basic method used to construct such a set of inputs is to record one's input while playing the game on an emulator, all the while saving and loading the emulator's state repeatedly to test out various possibilities and only keep the best result. To make this more precise, the game is slowed down. Initially, it was common to slow down to some low fraction of normal speed. However, due to advances in the field, it is now expected that the game is paused during recording, with emulation advanced one frame at a time to eliminate any mistakes made due to the urgency.

The use of savestates facilitates luck manipulation, which uses player input as [[Entropy (computing)|entropy]] to make favorable outcomes. Examples include making the ideal piece drop in ''[[Tetris]]'', or getting a rare item drop from a defeated enemy.

===Re-recording emulators===
Tool-assisted speedrunning relies on the same series of inputs being played back at different times always giving the same results. The emulation must be [[deterministic]] with regard to the saved inputs, and [[random seed]]s must not change. Otherwise, a speedrun that was optimal on one playback might not even complete it on a second playback. This desynchronization occurs when the state of the emulated machine at a particular time index no longer corresponds with that which existed at the same point in the movie's production. Desyncs can also be caused by incomplete savestates, which cause the emulated machine to be restored in a state different from that which existed when it was saved. Desyncs can also occur when a user attempts to match inputs from an input file downloaded from TASVideos and fail to match the correct enemy reactions due to bad AI or RNG.

===Verification===
Some players have fraudulently recorded speedruns, either by creating montages of other speedrun or altering the playing time, posting them as TAS or RTA. Because tool-assisted speedruns can account for all aspects of the game code, including its inner workings, and press buttons precisely and accurately, they can be used to help verify whether an unassisted speedrun record is legitimate.

One of the best-known cases is [[Billy Mitchell (gamer)|Billy Mitchell]], whose [[Donkey Kong (arcade game)|''Donkey Kong'']] and ''[[Pac-Man]]'' [[Guinness World Records|Guinness records]] were revoked in 2018, because he used the emulator [[MAME]].<ref>{{Cite web |last=Crecente |first=Brian |date=April 13, 2018 |title=Guinness World Records Disqualifies Billy Mitchell's Perfect 'Pac-Man' Run, Other Achievements |url=https://variety.com/2018/gaming/news/billy-mitchell-pac-man-world-record-1202752594/ |access-date=July 26, 2020 |website=Variety |language=en}}</ref>

In 2018, the world record for [[Dragster (video game)|Dragster]] by [[Todd Rogers (gamer)|Todd Rogers]] was removed from [[Twin Galaxies]] and [[Guinness World Records|Guinness records]] after an experiment showed that his 5.51 second time was impossible to achieve even with a TAS.<ref>{{Cite web |title=Dragster Designer David Crane Has No Doubts Of Todd Rogers' Record [UPDATED] |url=https://www.twingalaxies.com/feed_details.php/87/Dragster%20Designer%20David%20Crane%20Has%20No%20Doubts%20Of%20Todd%20Rogers%27%20Record%20[UPDATED]/1 |access-date=May 29, 2021 |website=www.twingalaxies.com |language=en}}</ref><ref>{{Cite web |last=Frank |first=Allegra |date=January 29, 2018 |title=Longest-standing video game record declared 'impossible,' thrown out after 35 years (update) |url=https://www.polygon.com/2018/1/29/16944736/atari-dragster-game-world-record-banned |access-date=May 29, 2021 |website=Polygon |language=en}}</ref>