Was going to be a short game, now is a proper campaign

I just need to take some thoughts from my brain and put them somewhere. Hope this is the right place.

Here's a (probably long winded) summary;

For the pandemic my friend wanted to play some D&D online. I haven't GMd in a long while, and that could have gone better but I wanted to try again. I grabbed a Hex Crawl pdf (I've horded gaming PDFs like a dragon so plenty of content to draw from) and the found an old school D&D clone rule book and got started with very little actual planning.

Session 0 was character rolls and a game of mad libs which was actually for a eulogy for a mutual, now dead, npc friend of the characters to introduce them to each other. DM pro tip: trick the players into coming up your important NPCs back stories. With a gift of an old farmstead from the will, they traveled to my hex crawl wilderness.

I had the sister of the deceased as the mayor of the major town in the area and arbitrarily had her demand 1000 gp in back taxes. What a great plot hook! It'll be good motivation for the characters to want to earn some quick riches in a dungeon they will soon learn about. What a terrible plot hook! (I could have just said "dungeon" and they would have dropped everything and gone there) This unfair tax really pissed off one characters (not the player) and he's  been plotting the downfall of the mayor ever since. Example; the players found some poisonous mushrooms and he's like "I know a good use for these".

The dungeon bought me some time but I need to fill out this city's government so it can be taken down. Crash course in Civics 101, please.

But wait! There's more! But this part is just me talking out loud, read or disregard.

If we continue on I need an end game to be building up to. The hex crawl has space vampires but no plot.

Original Dungeons and Dragons alignment system was only Law, Chaos or Neutral. There's a goddess, Mystra who maintains the weave of magic. I've been pulling from old Celtic myths and history with the southern Romanic peoples and gods impinging this northern territory. So I also have the Fey Otherworld as another plane to travel to.

Taking these separate ideas, here's what I'm thinking.

    There's an crystal island, isolated by sea and storm, that is The nexus of magic. It flows in and back out into the world, renewed. When you cast a spell, the reason you must spend time each day memorizing spells is because it's pulled back into the weave.

     A piece of crystal has been brought to the shores of a far off nation in a 9 element box. From it they grew more crystals. Drawn directly from the original, these are seed crystals. From these seeds more can be grown but none from those offspring. The Crystals of Law absorb magic and have power of their own, making new technology possible such as vehicles and weapons. Magic disappears from this nation and they grow strong but rigid in mind and rule, They conquer the continent. While they war with their immediate  neighbors, agents are sent across the Far Sea to gather intel and prepare for  invasion.

    One agent, away from the mind altering nature of the Crystals of Law, begins to love the freedom of this new home. While he breaks from his mission, he won't actively fight his sister. He will, however, find several free spirits and set them on a course to prevent this land from being over run.

You remember how I mentioned the Otherworld, a land of beauty, immortality and magic? It's beginning to sink/dissolve to sea.

I'm setting up hints for The Grey King, a goblin lord (played by David Bowie), to begin an attack on the valley the players are in. He's pretty upset that magic is being drained from his world. I think from that the players should get the hint something big is going on.