I've already posted in the Discord about this, but I feel it's important to post about it here as well.

Starting Monday July 18, 2016, any and all modifications of the UNDERTALE folder's files, including those other than data.win (but with the exception of the deletion of steam.api) will be officially disallowed in speedruns. Submitted runs with any alterations at all to visual components and/or in-game audio will be rejected.

Myself and others have come to the realization that the original "decision" to allow game file modifications in speedruns was hastily made. In fact, there wasn't much of a decision at all. Runners used them and submitted runs with them, and verifiers at the time didn't think much of it. For this, we are at fault.

The undeniable truth here is, modifications CAN be used to obtain an unfair advantage over other runners; the potential lies therein for somebody to gain time by modifying their game (examples including coloring sprites to make them easier to see, modding music for the purpose of being able to perfectly time tricks like PCE's, etc). And the potential for such, along with the gray area involved concerning what is advantageous/inconsequential to the speedrun (as well as the fact that people in the future may not be 100% honest with regards to their intents), warrants banning any and all modifications of the game's files in order to preserve integrity and prevent future runners from potentially gaining an unfair advantage.

We are not accusing anybody of anything here. If you used game modifications in the past, we are NOT calling you out. We're aware this is going to make some of you unhappy, and believe me when I say we sympathize with you. But we ultimately believe it's for the greater good of the Undertale Speedrun Community, and its future, to return to our original standard of all runners playing the same game as intended, with zero modifications, as if the game was just bought and played.

Be aware that current runs on the leaderboards using modified files will NOT be removed, out of fairness to those who used them when they were legal. (Since these runs were ultimately accepted by a verifier, file modifications in these runs are deemed to be inconsequential.)

If you have any questions, feel free to send me a message.

-TGH