Basic addition- Jet Ski Race: http://www.arcademicskillbuilders.com/games/jetski/jetski.html
Two digit plus two digit addition game:http://www.oswego.org/ocsd-web/games/Ghostblasters3/ghostadd3.html
Subtraction:
Basic subtraction- Mission Game :http://www.arcademicskillbuilders.com/games/mission/mission.html
Choose hard, medium, or easy to practice addition and subtraction while playing Math Baseball!