Team Fortress 2 / Left 4 Dead 1 & 2: sub-1000 hours, each.
Subspace/Continuum: over 1000 hours for sure, but nobody counted. Tried jumping back in the game just for fun, i'm back to square one "what's the button to attach?". I was a Trench Wars/Extreme Games pub guy.
EDIT: First post in a two years-old lurking account. Hello, world!
Same here. Just under 1300 hours in Rocket League. Quit after the move to Epic. I'm sure the community is fine, but in my opinion it's on a downward trend now.
There was no real breaking changes since Epic bought Psyonix IMO. Although they quickly retired support for their native Linux and Mac builds after the buyout (that, i'm pissed about. still playing on a virtualized Windows machine with GPU passthrough, but I suspect this is on borrowed time before they ban that). But since then, game went free 2 play with only seasonal cosmetic items you can get. Core gameplay is still fun!