In the latest production update to We Happy Few [Official Site], the developers note it will have another delay from going April until 'Summer 2018'.
It's a shame, but good games really do take quite a lot of time and effort to make. Have a listen and watch a little new gameplay too:
On top of that, they've also said they're disabling Steam store purchases as of February 1st, that way people can't buy into something that's going to take a while. Not only that, but the Early Access version is obviously going to be nothing like the main release.
They will also now allow anyone to refund it, regardless of time played.
I have to admit, I really like how genuinely honest Compulsion Games seem to be. Not just in their words, but their actions with the above points really make me like them.
As for the Linux release, last we heard it will be after the full Windows release but they're still commited to doing it and they've been developing the Linux version themselves.