While Nestopia requires more power to run than most NES emulators, it is also the most exact NES emulator available for Mac OS X.
Nestopia is an open source Nintendo Entertainment System emulator that was, like all of the best emulators, ported from Windows to Mac OS X. If you ever owned an NES and want to play some of your old games without having to pull that dusty old box out of the garage, this is the software for you!
Emulation, ROMs and Legal Stuff
While Nestopia as software is not illegal, ROMs can be in certain situations. If you own the hardcopy of an NES game, or the copyright of the NES game has expired, or it is a home-brew NES game, then you can legally download the ROM. However, if one of these conditions is not met then downloading ROMs is illegal. Please DO NOT ask Bright Hub or this author for links to NES ROMs. You will have to find those for yourself and deal with whatever consequences you may face. Now, lets move on to the important stuff!
While Nestopia is not as loaded as other console emulators (ZSNES, for one) it still does its job respectfully. When you first open it, it will prompt you to load a ROM (either the most recently loaded ROM or one from a certain folder). Once the ROM is loaded you will have a few simple options. You can increase the size of the window to full screen (which is recommended since the Nestopia window is hardly bigger than the average internet avatar). You can also take a screen shot or freeze a game state easily by clicking on the Options menu. Within Nestopia freeze states are really the only way to save games since most NES game didn't come with save points to began with.
There is also a useful preference menu within which you can configure the video, speed of emulation and other advanced options. In addition, you can configure your keyboard with the keys you want to use while you play ROMs.
One of the largest downsides of Nestopia is the lack of controller support. You can purchase Emulator Enhancer for USB controller support, but it costs $30 and I'm too cheap to buy it. Also, this emulator takes a minimum of 600 MHz to run. Not that this should be a problem for most modern Macs, but it may pose a problem for older ones.
Well, this all depends on how many NES game you own and how much you would like to play them. If you don't mind using your keyboard (which gets easier the more you do it anyway) you can relive a lot of those old games without having to spend $5 and up a pop to buy them on the Wii Virtual Console. I find it very useful since I like to play a home-brew NES games and weird games from all over the world whose copyrights have gone under (and the occasional round of BurgerTime, which I do own a hardcopy of).
For Mac OS X NES emulators this may be as good as its going to get for a while. Unfortunately for Mac users we don't have a lot to choose from in the NES emulation department. But, Nestopia gets the job done, so I really can't complain. However, USB controller support would be nice if it were included.