I am in the prototyping phase of making a puzzle game for iOS. The basic premise of what the player has to do is get from point A to point B by navigating through a maze like setup, while moving blocks out of the way, and avoiding enemies. This is my first approach to a game like this so I am wondering how others have made sure that the levels they create are solvable.
For example take the classic Unblock game where you have to move the red block off the game board by moving the other non red block pieces out of the way. It gets difficult because they are all in a tight space with not much movement to be had.
Has does the creator know that the arrangement of puzzle pieces are placed in a way that makes it possible to solve the puzzle? Do they start with paper prototypes and work from a solvable end state backwards to make the initial game board layouts?