This program is one of many revised versions of the popular game Super Mario where your goal is to collect as many coins as you can while avoiding any contact with incoming enemies. The faster you complete your challenges, the higher your final score gets.
The main difference between this revised version and Nintendo's Super Mario Bros. is that the first one enables you to shoot your gun and create a portal (takes you to another location on the scenery, drops bombs, etc.). You won't see any graphic differences between the two of them, even the background music and levels are the same.
Besides providing you with numerous missions, this application also brings you an integrated level editor. You can include a wide variety of items in your missions, like background elements (clouds, bushes, water, etc.), additional coins, platforms, power-ups (for example, mushroom which increases Mario's size), and many other.
A good thing is that this app also offers you plenty of settings to change Mario's appearance, the screen resolution, sound volume, etc. What's more, you can configure the control keys options according to your needs.
Therefore, I can't find any reason why you shouldn't at least try this amazing Mac app, especially when you don't have to pay a dime to use it.