A lot of free flash games can be downloaded for offline play with just a bit of internet knowhow. For example, this one was linked around these parts a few days ago, and I've been playing it heavily since:
http://www.gamedesign.jp/flash/dice/dice.swf
You can right-click that link to save it to your computer.
http://www.gamedesign.jp/flash/dice/dice.swf
You can right-click that link to save it to your computer.