ActionScript 3.0 and Flash Player 9 were released recently by Adobe. Both of them have changed tremendously compared with previous versions. Now ActionScript 3.0 provides a consistent, powerful, and sophisticated Object-Oriented programming language for the Flash Player runtime environment. The currently released Flash Player 9 contains a new ActionScript Virtual Machine, called AVM2 , that uses a redesigned bytecode instruction set. This provides significant performance improvements over the previous AVM1. ActionScript source code is compiled into bytecode format by a compiler, such as the ones provided by the Flash Authoring tool or Flex SDK. The bytecode is then embedded within a SWF file, which can then be executed by the Flash Player. I authored the Music Notes Catcher game as a case study in order to compare its design, implementation, and performance in ActionScript 2.0 and ActionScript 3.0.