Slightly confusing, but rich and fun.
While I find the interface a little confusing to use with Fourth graders (lots of text) I think Argument Wars ( a game on Sandra Day O'Connor's iCivics) gives a decent overall experience with building a case and using supplemental texts to win an argument. The graphics are flashy and crisp (even if the characters design is a bit strange). The only thing I think could be improved is the audio options for students with lower reading levels.
How I Use It
I have had Fourth graders using it for the last two years. I walk around the class and coach them in their decision making asking them to look for key concepts when picking their evidence sources. The students find the game engaging and fun and I've even had students request to play during free time.