I worked through most of the levels but finally gave up. The physics in Implode! XL is simply too unpredictable to enjoy the game. I was playing in expert mode, and I found that moving just one bomb the slightest amount would often result in a completely different result. There was no way to predict what would happen, which is kinda the point when solving a puzzle. I ended up solving many of the challenges through trial and error and sheer luck, not with critical thinking. The physics is also prone to errors. In some cases, parts of the structure would defy gravity and remain standing on one column. The 5-second timer would sometimes cut off a challenge that was still in the process of falling down. As for the scoring, it seems arbitrary. To get an A+ score you need to exceed the maximum dollar value assigned to each challenge. In some cases, I was able to get an A+ score on the first try, whereas in other cases I spent an hour fiddling with the placement of the bombs but could never get more than a B score.