My idea consist (if it's possible to make) on a help button near the simulation options that opens help pages when you click it. This pages would be useful for new TPT players. This pages may contain something like a mini-guide and links to the official page, the forums and the wiki, for example:

Page 1- It could contain instructions saying: "Welcome to The Powder Toy, a sandbox simulation game without direct objectives. If you are a new user, try to learn the functions of the elements (every element has a function and a reaction with another one, if you want to learn more about them check out the wiki), play some user created levels and have fun. Before creating a save and publish it we recommend you to read the rules (page 3) so you don't have any trouble with your first save." More or less this page is like a welcome for the new users, but it isn't necessary at all.

Page 2- It would contain instructions for the shortcuts, like the ones that appear at the start but more detailed (like the ones of the official hotkey list: https://powdertoy.co.uk/Discussions/Thread/View.html?Thread=2259). "Z for zooming/ B for decoration layer/ etc". It could also contain a link to the list of known bugs.

Page 3- Rules for publishing.

Page 4- Some users don't know about the discussions, the wiki or the IRC channel, so in this page there could be links for this pages and some description about them.

Page 5- Credits: contributors.

Hope this idea helps!