Old School Revival or Old School Renaissance.

The original open gaming license let indie developers use the d&d ruleset prior to Advanced D&D. The OSR is built on these rules as a foundation.

There are a ton of projects ranging from just makng the original rules easier to read to building whole new campaign settings and layers of new rules. They are all generally compatible with each other and classic published d&d adventures due to the shared core foundation.

The RPG Pundit is an author and big promoter of the OSR. He's a bit of an anti-woke firebrand, as well.