People like to hate on this game, and yes, the game not being able to tell if you completed a challange or not is a downside, but I still enjoyed it. The best way to play Stack-Up is actually in the 2 player versus "Bingo" mode. Both of you are competing against each other for the control of ROB. Jump on squares five in a row for a command and ROB does that command. Yes, ROB, moves a bit slow, but I actually had some fun with friends with this game mode. We even had a laugh of loud moment when we found out that running into each other causes our characters to spiral off screen! It's a decent puzzle game that gets hate because it uses ROB.