The Achievement patch is almost ready, which will bring over 200 Achievements and a few other small changes and bug fixes.
An early version can be tried out by enabling the "Test" branch of Chester One from your Steam client. Just right click on Chester One in your library, choose Properties, and then the Beta tab. Select the Test branch from the dropdown and the update should start to download.
The patch will go fully live sometime soon, main holdup is the 200 + achievement icons I now have to create. Oops.
There is no plan to reset Achievements with the full launch but if something does go horribly wrong before then there may be an Achievement wipe.
Edi: The achievement patch is now live! Most achievements are currently using placeholder icons that will be updated in future patches.