4pm GMT, 24th March 2025.
The release time for Atomfall Deluxe is 4pm GMT, so about 1 and half hours from the time this document was created.
Steam may inform you that the date is 27th March, but this will change in the next few hours when the early access goes live.
Once the game is released, after 4pm you might need to exit and re-load Steam to see this.