I'll give you three off the top of my head, there are many more around for sure.
Rimworld developer shares an open changelog for the game development, updated almost daily.
docs.google.com/document/d/1_rCdGYp3nbSUXFG4Ky96RZW1cJGt9g_6ANZZPOHyNsg/pub
Rust developer shares everything they are working on.
trello.com/playrust
Amplitude studios has design discussion forums that help shape all their games, issues get voted on and dev implement features that are most needed by direct feedback from players.
http://forums.amplitude-studios.com/forumdisplay.php?8-ES-GAMES2GETHER-Design-Discussion
Open development isn't new.
The only difference is that CIG has attracted so much hype with SC that now even people that have slept under a rock the last 5 years know that open development actually exists.
Oh, and we forgot the most important one. Limit Theory. Technically the guy puts out more development vids and updates than even CIG, per capita. (Considering there's only one person working on the game.)