any chance theres gonna be a demo or playtest before release ?

Both the short description and the expanded description on the store page mention co-op, but not solo. The store page claims "Built from the ground up for co-op". So the questions are: 1) is it playable solo, or is co-op mandatory? 2) is it balanced to be playable solo? Because recently there have been multiple games that, while technically playable solo, are unplayable solo because the difficulty is balanced around co-op....

the discord banner has what looks like a pirate?

This reminds me Gauntlet, but with a more action vibe. Is there a campaign and an endgame?

The game looks really good and I want to play it with my friends. How many players can play together?