/vg/ also had a pretty cool amateur game dev general thread (/agdg/). No one was making any hidden gems there, but it wasn't trash either. At any rate, I liked it.

Not hidden gems, no, but some of big titles originated from /agdg/, both Risk of Rain and VA-11 Hall-A started as progress posts in /agdg/ before hitting combined >1M sales.

I remember one user who made a really fun arcade flight simulator.