I loved Shadow Wars. I picked it up when Target had it on sale and put a good 35 hours into it. The story isn't the greatest, but you will have so much fun playing through the maps and leveling up your characters that you will forgive any of the minor flaws like that. If you like turned based tactical games it is a must buy.
I'm tempted to grab Monkey Ball. I haven't played one since the Gamecube and the price seems right.