Looked through the steam announcements to find the codes
0.1 ver. code: supermutation (Travel update)
0.3 ver. code: AccessBuggyJunglePreview (Jungle update preview)
0.4 ver. code: buggy_mountain_preview (Mountain update preview)
0.5 ver. code: buggy_0.5_preview (Pattern update preview)
0.5.5 ver. code: release_preview (Release preview)