what do we need to live?
Spiritual/astral energy and water. Since you lack the former in this world, you have to focus on the latter in excess. This was a mechanic I planned to introduce later on down the line.
What do we have?
Specify.
Are there any resources other than sand and stone?
Yes. I mentioned oases (water), and land yet to be discovered which means the entire world isn't sand and stone. Honestly, the write-in kind of contradicted itself, so y'all can find somewhere else to make a settlement or I can work something into the current one.
Do we have any difference from humans?
Yes. On average, Mystics have four or six arms and feelers which they use to communicate and for sensory purposes. And tails, which aren't furry and skin-only like the rest of them. Three eyes (you can guess where the third one is), and odd skin tones.
How many of us are there?
About 100.
Do we control a specific Mystic? Or are we some invisible, outside controller?
You control a 'silent protagonist' Mystic. You're a director. Name, appearance, such on? Unimportant. For the time being.
What are Mystics like, compared to humans?
See above.
To Everyone: Update shortly. Just checking my email and other important stuff. Keep in mind the SG is starting out
light, so when you information such as that, you're treading into territory I have yet to map, figuratively speaking.