Have you ever played a game and the kids are just begging to play one more time? Great! That's wonderful! But it is just the time to stop playing. You don't want to wear the game out until they are sick of it. Play it just long enough to have a good time and have them wanting to play again. That way next time you pull it out, they will be eager with anticipation.
Games are a great way to review and reinforce certain concepts and sometimes even just for fun. The internet is a great resource for games of all types. Pinterest is also becoming a great place to get ideas and also a great way to organize them. Just remember variety is key. Use different games, play them different ways - do anything you can to make it exciting and fun. They are much more likely to remember something if they had fun while learning.