The MAME emulation program is only for legal use with game ROMs from arcade games and boards you already own. If you download game ROMs from the internet and do not own the boards or have legal authority to distribute the ROMs, you are violating several laws I won’t go into here.
Mind you, some older game ROMs have been made free to the public and may be distributed at will. You can probably find more information on those ROMs at Classic Gaming and other sites.
I will also offer, apropos of nothing, a personal anecdote. I’ve never personally heard of any legal action taken against ROM distributors within the United States, but that doesn’t mean they wouldn’t or won’t if do.
Also by way of anecdote, I’m surprised the legal authorities don’t go after the people sharing these ROMs on services like KaZaA. I’ve heard they’re everywhere, and it seems to me that they’d want to put a stop to it.
Also apropros of nothing, I’ll mention that I’ve heard there’s a group of folks out there who have amassed every single MAME ROM that’s ever existed, and will make copies freely and distribute them to whoever asks. All that’s required of you is to provide them with the blank CD-Rs needed (around 30+) for the task.
(And no, I am not one of those folks. Just something I’ve heard, is all.)
A lot of these sites post a disclaimer that states (approximately) that you are allowed to download the ROM, but, if you don’t a copy of the original game (like you have the room!), you must delete the ROM in 24 hours.
30 CDs worth of files? That’s almost 20MB. I thought the ROMs for the old games were tiny, like four kilobytes. Are there just thousands of games out there, or are some of the ROMs for newer, larger games?
There are also regional/licensing differences, and niche games that the west rarely see. “Super Sexy Strip Mahjongg, Asia edition,” “Super Sexy Strip Mahjongg, Americas edition,” “Super Sexy Strip Mahjongg, Europe edition,” etc.
As far as PLAYING games goes, it’s like owning your own arcade.
If you use the windows front end for it, you have an explorer like window that lets you select the game. When you launch it, you can play it windowed or full screen. Preferences allow you to play it with nice little touches like scan lines.
You can use whatever direct-X compatable controller you like. My favorite is a PS2 controller with a KIKI Joy USB adapter. Having 2 joysticks makes playing games like Battlezone or Robotron or Smash TV an absolute blast.
As for the games themselves, they are the originals. It’s just like playing the arcade versions except that you can pause and you don’t need quarters. There’s also a way to have high scores reported to a central location for comparison.
MAME is a really fun thing to check out especially if you are an arcade rat from the 70’s and 80’s.