All you need for an unlock system is a button to click on or a specific keystroke to be detected; after which a separate world is started for character selection. You will need to pass the player whose character is to change to this selector world. For example 'Greenfoot.setWorld(new CharSelect(this));' from the player class. Then, receive the actor in the CharSelect world with 'public CharSelect(Actor actor)' as the constructor declaration. Now, you can use 'actor.setImage("...");' to change the image and close the selection world out with 'Greenfoot.setWorld(actor.getWorld());'.

Hi there, Kage! Greenfoot is not a program that allows for instant games just the way you want them. To properly utilize Greenfoot, you need a decent knowledge of programming in java.

Are you saying that what I gave was too advanced for you; or just making a comment? If the former, then do what you can; and if having specific problems, post again with tried code and what you need improved.

Are you familiar with java coding at all? Have you downloaded the Greenfoot application? Have you looked over any of the sample scenarios and their related code?