You can test the physics of your creation and this is very amusing. It does this by letting you actually use the vehicles you have created.
My son and I loved messing around with the Lego Digital Designer, but Brick Rigs lets you take things a step further. Not to mention the fact that the game (well on my PC) seemed to have a fair bit of trouble staying smooth when there were a ton of bricks on the screen at the same time. There is an online component to this game, but I found the community to be a bit on the exhausting side. We both have pretty weird imaginations so we were coming up with all kinds of crazy stuff. I had a great deal of fun playing through this with my son. You start off with one thing and then it quickly turns into something else. This ranges from normal cars to tanks to a pretty over the top railway system. I have messed around and made all kinds of crazy stuff. There really is no limit to the kind of vehicle you can come up with in Brick Rigs.