Confirmed release information
The official Steam store and launch announcement list August 18, 2026. The store exposes Windows requirements and a SteamOS + Linux section.
Launch status is a separate field
A calendar date alone does not prove that a store has unlocked. At 9:00 AM PT on August 18, the official Steam page listed Stackmon as released and available to purchase.
Version information available now
The newest numbered full-release patch found is 9.0.97, posted September 17 after 9.0.91 and the preceding 9.0.901 save-loading hotfix. The separate Steam Demo was retired after launch; its 7.0.33 record remains archived rather than being presented as the retail version.