Sonic and Mario have always had a rivalry, because Sonic is the flagship character of Sega, while Mario is the flagship character of Nintendo, so the two of them have always been at odds. Still, they might be rivals, but they are the kind of rivals that respect one another, so when one or the other is in trouble, they always are to help. That is why when Mario is in a pinch, Sonic will come to his rescue, just like in the new and awesome game called Sonic Rescue Mario.
As you might have already realized from the image of the game, this is a platform-adventure game where you have to help Sonic get to the end of each level, which is a door at the top, making sure that you get through all the doors at the end of each level, finally reaching Mario in order to rescue the plumber. Along the way, there are monsters as well as traps and hazards that you have to make sure to avoid at any cost!
Move and jump using the four arrow keys. Use things like boxes, or jumping items to advance, moving up through the platforms, and, as you approach the end of each level, try to collect as many of the rings you encounter as possible, because they represent your score, and we've got no doubt at all that you will clear all the levels with a whole lot of points as well!