The closed beta was given to a select few who signed up last year, who have been able to play through an initial demo level of the game this past month.
Community manager Matt Gartzke gave
[a] big thanks to everyone who participated in the Minecraft Dungeons closed beta, announcing that Mojang's feedback site and bug tracker would be ceasing submissions for Dungeons until its release on 26 May.
The game is currently available for pre-order, coming in two different editions. The standard, base edition of the game costs US$20 while the Hero Edition will cost US$30 and includes two DLC packs and some cosmetics.