ARK: Survival Evolved has now set an official date as the 25th of June for the release of the Linux (and Mac) versions.
I am rather excited to give this one a go, even with it being early access and not too optimised just yet.
They answered it officially on Steam here.
QuoteYes! We’re excited to announce that we can finally confirm the release date of the Mac and Linux client to be the 25th of June! We can’t wait to see our buddies from other platforms join us on the ARK! Hopefully you’ve all kept in touch and informed via the announcement page and you’re ready to begin your journey :D
About the game
As a man or woman stranded naked, freezing and starving on the shores of a mysterious island called ARK, you must hunt, harvest resources, craft items, grow crops, research technologies, and build shelters to withstand the elements. Use your cunning and resources to kill or tame the leviathan dinosaurs and other primeval creatures roaming the land, and team up with or prey on hundreds of other players to survive, dominate...and escape!
Check out ARK: Survival Evolved on Steam, but don't buy it until the Linux version is actually released. Seems pretty solid, and it's a shame the sale ends before the Linux release. It's pretty tempting even for me to buy it when it's cheap.