Educational game to practice the four basic math operations

Tux of Math Command
Free
Offline
http://tux4kids.alioth.debian.org/

Tux4Kids develops high-quality software for kids, with the goal of combining fun and learning into an irresistable package. Our software is free: you can download it for use at home or onto hundreds of computers in a school. We support all major platforms, including Windows, Macintosh, and Linux/Unix. Our programs are used by people around the globe, and they have been translated into dozens of different languages. As open-source software, these programs can be freely extended or customized, and they are supported by active communities of volunteer developers.
Whether you're a parent, a teacher, or a kid, give Tux4Kids software a try!