I know it's a lot newer, but my nomination goes to Icarus this time. They've kept up a weekly
patch-with-accompanying-dev-diary cadence for three solid years (they're just celebrating an anniversary this week, in fact), talking about changes and additions and why they're being made and what they're working on for the [near] future with full timeline updates... I feel like other games that have done that sort of thing for much shorter periods have had a lot more recognition than those guys, so this small gesture is the least I can do.
But I am impressed by their persistence in what they've actually accomplished with the game as much as I am about their communication of it. There was plenty of residual DayZ hype that helped them quite a bit in the beginning, but when the game wasn't what most people apparently expected -- as well as somewhat janky -- interest nosedived and they've been working this whole time to rebuild player trust despite dwindling engagement and revenue. Although not every update is a big one, I'm sure they could be if the time between releases was lengthened similar to NMS. And all that effort involved reworking everything into a very different alternative game mode (persistent open-world survival), requiring a lot of tweaking and testing to make it more congruent/performant for long playthroughs involving voxel-based mining and modular base-building in Unreal 4, and now includes all map areas plus all structured mission content (much of which was only ever meant for the original session-based extraction loop).