The first instalment is Once Upon A Wizard's Shelf: Take control of a living spellbook, let loose in its master's infinite Wizard's Tower! Make sure your shenanigans don't mess up the Wizard's stuff, and they might just let you live when they return from whatever it is they're doing. All you need to play is the Player's Handbook, the Monster Manual, and this PDF!
There will be other instalments of Niches & Nonsense coming in the future, though they're "ready when they're ready" on no specific schedule. The next one will be about dragons destroying villages, so...watch this space!
On the business side of things, I'm counting this as a "small" creation because, whilst it's more than 5 pages, many of those are playsheets/non-game stuff or random tables... So I don't feel right charging for it. That means Once Upon A Wizard's Shelf will go out to the public in a month's time, and that you lovely INITIATE+ folks get it a month early!