Tap on the colored rescue vehicles to push all the enemy vehicles off the screen. The city was invaded some bad cars which are not up to anything good. So the cars who are in change to defend and protect the city will have to get rid of them. In each level there are a few bad cars. You can click on them to make them move of the platform, or you can click on the good cars to make them push down the bad cars. In any case your only target is to get rid of all the bad cars in order to advance.