Question: Related: [When is it allowable to change the rules?](https://codegolf.meta.stackexchange.com/q/1346/3808)

As noted in the linked meta post above, it's typically particularly frowned upon to significantly change the rules of a challenge after posting it. There's no hard and fast rule on this yet, so the purpose of this meta post is to enact at least some kind of **policy to determine when drastic edits should be rolled back**.

Here, we define "rule change" as not any type of edit but **any edit that causes one or more reasonable hypothetical answers to become invalid beyond repair**. Note that the "beyond repair" clause means that this *does not include* minor rule changes such as input/output format. Note that the wording of this definition also (intentionally) does not include edits that give answers *additional* liberties.

There are a few "poll-style" answers here to vote / comment on:

* [Should rule changes that don't invalidate existing answers be allowed?](https://codegolf.meta.stackexchange.com/a/7778/3808)
* [Should rule changes that invalidate one or more existing answers be allowed?](https://codegolf.meta.stackexchange.com/a/7779/3808)
* [Do rule changes in comments count?](https://codegolf.meta.stackexchange.com/a/7780/3808)

Adding your own answer is encouraged, though, possibly addressing some of the following questions:

* Exactly what it says in the title: If you do think that some rule changes should be acceptable, which ones specifically and in what situations?
* If we're going with "rule changes are only allowed if they're minor enough," how do we define a "major" rule change?
* If you think the policy should be something other than something that was mentioned here, what is it, and who gets to decide which rule changes are allowed?

Answer: 
Rule changes that invalidate existing answers should be allowed (they should not be rolled back).

*(Upvote if you agree, downvote if you disagree, and comment for anything else.)*
Rule changes in comments are equally valid as those that have been edited into the actual post.

*(Upvote if you agree, downvote if you disagree, and comment for anything else.)*