Novice programmers often struggle with many concepts underlying computer programming. The concept of a program variable that is, a named storage location is a centerpiece of the programming languages typically taught in introductory computer science courses including C, Java, JavaScript, Python, and C++. However, to date empirical studies suggest that misinterpretation of the state of a program remains a primary source of errors by novice programmers. We address this challenge by defining a game-based approach to interactive program debugging and by emphasizing the concept of program state in our approach. We specifically chose the metaphor of the popular "Space Invaders" videogame to provide a visual interpretation that reinforces the notion of program state in a way likely to be attractive to college students majoring in computer science. Our visualization technique and the resulting toolset are intended to steer students toward a debugging mindset centered on read and write operations of program variables. Here we discuss the key aspects of our game-based debugging approach. We also report preliminary results from field studies with actual college students who used our toolset to debug simple programs in which we injected faults.