This applied research proposal involves the development of a Digital Prototyping Tool for Card Game Design. The tool will support the creation of a wide variety of card games, ranging from variations on existing card games like Poker, UNO and Hanabi, to conceptual Card Decks for supporting design tasks. The tool should allow the easy creation of card decks, including simple designs for numbers, colours, names, types, figures, etc., but also the rule-sets of the games. Because this is done within a formal framework for specification of card games, it will become easy to modify characteristics of cards, and more importantly, the rules of the game, such as move protocols and game mechanics associated with certain types of cards. The tool will also offer support for playing and playtesting the game on screen.