Hey all, so I am currently making a homebrew gameworld called the Half-Moon Archipeligo for my RPing group's future campaign with 5th ed. This gameworld is connected to FR (specifically a portal out in the ocean near Waterdeep) just so you know what lore I am using, what gods, spells, etc.

I intend to run this game as a sandbox, and as such I am coming up with some major events that will be happening behind the scenes in the game world until the PCs come across it, if they do at all! My plan is to have these events occur unhindered if the PCs never run across them directly, or the NPCs involved in bringing them about. Some example ideas I have so far are. . .

1. Very influencial Dragon Cult will attempt to overthrow the established government in Half-Moon, they will succeed unless the PCs stop them, or they will also succeed if the PCs HELP them :) I figure this will happen around level 6-8.

2. Powerful Necromancer is building an undead army because he/she has prior knowledge of an impending invasion from another plane (demon armies, or something of the like) and thinks only hordes of undead will have a chance of winning. The PCs will likely either try to stop said Necro, or maybe will believe them and try to help. This will happen around level 11-13

3. The impending demonic invasion itself! Probably happening around level 15-16

Basically, I am asking if these events sound interesting? The game world will endure no matter what happens. If anyone else has ideas for big, world changing events like these, I would love to hear them. Better yet, if any of the fine folk here can think of smaller events that might not change EVERYTHING, but could still influence Half-Moon, I would love to hear those too, as I am having a hell of a time thinking of small fries. Sorry this was so long, and thanks in advance for any and all responses!