These are the current rules:
No sexually suggestive content or foul language
You are not the first person to make a penis-shaped airplane. The joke is old and boring now.
We are not going to moderate every curse word, but please try to keep it clean.

Don't abuse the voting system
Don't tell someone: 'If you upvote my stuff, then I'll upvote your stuff.'
Don't make alternate accounts to upvote your own stuff.
Don't beg other users to upvote your stuff.
Don't cancel challenges that have successor points.

Regarding Posts
Don't post the same thing multiple times.
No more than 3 public airplane submissions per day. No more than 10 unlisted submissions per day.
No sympathy posts or memorial posts. Move those discussions to the forums.
We allow a wide variety of uploads that are not actually airplanes. However, we do reserve the right to remove posts if they are too far off-topic.
Don't spam other players' posts with links to your stuff.
Don't use offensive symbols, unless they are necessary for historical accuracy (ie - Swastikas should only be used on things like a WW2 German Bomber).
While we allow photoshoped thumbnails, post with misleading thumbnails will be removed.

Don't abuse the post reporting system.

Politics and Religion
Please, remember that this is a game about airplanes. While we do allow off-topic conversations in the forums, if you talk about religion or politics then there is a good chance that your post will be removed. Especially if we feel that it is likely to stir up debate.

Be kind
Be friendly to new players!
If you are continually telling people their airplanes suck, then maybe you suck.
No hate speech. You will be banned immediately.
Please, just be courteous.

Blocking players is okay
It is every player’s right to block whomever they wish for whatever reasons they wish.
Being blocked by a user in no way hampers your ability to enjoy the game or this website. If someone blocks you, be a better person and simply move on.
If you retaliate in response to being blocked, then you will be banned. Do not post or comment about a player who blocked you, about a specific player who blocked a friend of yours, or about a specific incident about specific people involved in blocking one another.

Tweaking airplanes is okay
It is okay to download someone else's airplane, make some tweaks, and re-upload a new variation.
In fact, the original designer may even receive bonus points.
However, if your variation does not offer any improvements over the existing airplane, then it may be removed.
If you are circumventing the predecessor/successor system, then you will be banned. Never upload a successor as an original design; give credit to the designer of its predecessor.

Naming your airplanes
Don't name your airplanes for a YouTuber. Instead, give it a cool name and use the tag system. It looks less spammy and the tag system makes it easier for YouTubers to find cool planes.
Example of a bad name: JELLY CHECK THIS PLANE OUT! [No Tags]
Example of a good name: F55 Super Dasher [YouTuber-Jelly]
Be courteous if you find a violation of this rule. New players may not be aware, so just link them to the rules and tag a moderator.

If I may, I'd like to propose some additional amendments to these rules. First, they tend to be quite vague. For instance, "Be kind" or "Be courteous" are somewhat open ended. While I know basically what this entails, I know there are people with significantly less common sense that would either try to bend the rules or just ignore them completely and think that telling people their planes are bad is being kind. Secondly, I think there should be a rule about repeated offenders. From what I've observed, someone who has broken a rule is much more likely to be punished for something minor in the future. This should be spelled out in the rules. Maybe make a link to Andrew's "Where do you stand?" forum in there. Third, the punishments are vague. While some violations like hate speech, thumbnails, off-topic things, politics and religion, and circumventing the successor system have spelled out consequences, others do not. This causes players to question moderator decisions as they do not believe those violations are enough for them to be banned, striked, etc. And in the interest of limiting the questioning of moderator decisions I know this would be a smart choice. Fourth, I have a couple new rules to suggest. Those rules are as follows:
1. No intentional starting of drama. While the question of intent is usually the reason people get banned or striked, I think we should outline it more clearly to warn people. Add examples of starting drama such as making a forum calling out a particular user/users or questioning moderator decisions regarding banned players. Nowhere in the rules is the word "drama" even mentioned, so in essence this rule is being enforced without being a rule. A "phantom rule", if you will.
2. A truth rule. If someone does call out a user for being a jerk to other people, they should not be penalized. While I agree the forum should be removed to avoid drama, if someone is posting pictures of their comments that harass users, then that is not slander nor libel (It would never be slander because slander is verbal). Since unedited pictures would not be false, it should be accepted as reporting. If it is found that they either used the report button with no effect or did not know how to utilize the report button on comments or posts, then there should be no punishment, just a warning to report it on an unlisted post next time.
Sometimes, what was a good intent turns into a ban or strike because someone was trying to report something they felt the moderators had been annoying for some time. While this may not be true, we can't discount their efforts to bring someone to justice. I like the new strike removal policy, and I hope that when the rules are revised to add that policy and the third party harassment rule that these suggestions are taken seriously.