Kaphod Kerblebrox

Alright! Had more time to dig into this, uninstalled/reinstalled of KSP and I'm on 1.6 now.

No, I do not believe I'm using the Proton Beta, that rings a bell and I might have tried getting it running... but apt just shows I'm using steam:i386 (doesn't seem to be another option, but my actual run-time shows the KSP.x86_64 bin) And the Steam client indicated I wasn't opt into any betas (and opting in didn't help) To clarify, I do get old versions of the game, just neither 1.5.1 (presumably because I'm running that version) nor 1.6

Don't think so, I don't get either 1.6 or 1.5.1 as an option.

As the title says.... Is v1.6 for Linux actually released? I play on two different computers, one Windows, one Linux. The Window system got the update to 1.6 first, there were some complaints about mk2 Lander but it all worked out in the end. Later that same day I went to play on my Linux system and I *thought* I had update dialog telling me about 1.6, doing upgrade, etc. I played, got the same warning about the lander and some other parts but it worked. Then trying to play again the next day I get incompatible save errors and it won't load. I started investigating this thinking the save had been corrupted only to realize I'm still playing 1.5.1 Now I'm wondering, did I imagine my Linux system updating? Did it revert? Is it even out?

I experience the same on a similar system. Ubuntu 18.10 Intel Core i5-4570S @ 2.9Ghz 8GB RAM Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller Makes landing pretty difficult, usually taking 4 or 5 tries because it's so choppy.