
I sell games and libraries for GameMaker. My libraries come from internal tooling that I built for myself over the years to help with my own game development, which I've turned into proper libraries for public use. Things like stat managers (Catalyst), pub/sub tooling (Pulse), state machine handler (Statement), getting a freaking functional textbox running for GM (Quill), weighted randomness (Fate) and dynamic narrative handling (Whisper).
I've spent a lot of time working on and with these tools and have made them as easy to use, while still keeping them as flexible as possible (I am a lazy dev, lol, and I like it when things are quick and easy to setup, but don't prevent you from expressing stuff the way you want).
Want the best bang for your buck? Pick one of these and get a substantial discount:
Ignition Kit (Essentials)
A focused starter bundle of core drop-in GML libraries that every game can use (has Statement, Pulse, Catalyst and Echo).

Full Suite Pass (Complete libraries)
One purchase gets you everything: every current library, plus future releases as I launch them. The price goes up as the library grows, so buying early locks in the biggest discount.
Dice Trek (Wishlist on Steam!).