Firstly, I'm not an expert at coding, so if there's any technical limitation holding you back from creating any of these, let me know.

Symbols:

• Thin Islands

Inverted ravine generation. Takes a block or biome modifier. They'll spawn similarly to Spheres in that they can be found floating in the sky in an age when the page is used.

• Biospheres

Hollow glass orbs that take a biome or block modifier (similar to Floating Islands). Inside the orbs are terrain, made from the biome or block specified.

Biospheres will use the same terrain type as the rest of the world (e.g, a world with Standard World landscape will have biospheres with the same terrain type)

• No Libraries

Disables library generation in a world. Useful for customized/themed worlds or for server owners.

• Purified Atmosphere

Voids all negative status effects upon entering an unstable age. Other forms of instability will become more intense for every voided effect.

This effect can only be added by using a page, and will not occur naturally.

Tweaks:

• The "Spheres" page can take a Size modifier (Huge, Small, Large, Tiny, etc) to modify the size of an average sphere.

• Make the "Maze" symbol a world type

EDIT: Here's a couple more tweaks

• Biospheres can take a size modifier like spheres.

• Config option to disable random grammar from interfering (i.e, if I enable this config, an age will not have random extra features if at least one is specified in each category, so if I specify one type of sun, structure, etc, there will be no randomess except for when there is a dangling modifier or the maximum amount of biomes for a biome controller hasn't been met). Disabled by default.

• Perhaps some modifications to the way instability works? Instability can sometimes make ages unusable at the moment.

Thank you for the ideas! Right off the bat I really like the biospheres idea. I can tell you right now that I have no power to disable libraries. If I could, I would, because I want to improve them, but it is what it is. Everything else looks doable, though.

I wanted to give you a little update on libraries. While I initially thought I was impossible, I finally found a way to mess with them. The newest alpha release has an option to upgrade the libraries cosmetically or disable them entirely. Because there is no way to prevent the library generation in the first place, disabling them actually involves erasing them after they've been generated, but it still works pretty well.