Copy ‘n’ pasted from my post at MHQ:
Sounds are perhaps the most overlooked factor in amateur game creation. Of course, like any other aspect, they can make or break a good game. For a cartoony game like Super Mario World, those lovely, unrealistic sound effects work fine. And those are perhaps the easiest sounds to make, strangely enough.
But most of us Metroid fan game makers want a serious, perhaps even dark game. We can’t have a Mario-like “boing” when we jump, or a “wah-wah-wah” when we die. When Samus is running on metal, we don’t want to hear two blocks of wood smacking together, and we don’t want to hear the same thing when she’s running across marshy dirt. So what do we do?
We could rip the sounds from old games, but they often feel out of place and recycled when this is done. We could perhaps attempt to recreate the situation physically and record the resultant sounds. To do that, you would most likely need a better microphone than the $10 piece of junk you’ve had for years. You could try, like the professionals, to find things that could make sounds similar to the desired ones. Again, this requires a quality microphone. You could perhaps utilize a program like DrPetter’s sfxr for some retro, low-quality sound effects. Alternatively, you could try to locate the sounds you need on a royalty-free sound effects website. But there are just so many possible sounds out there, and there are so many possible variations of any given sound!
[Insert discussion here.]
Oh, and here are a few sound effect websites I’ve looked around before and actually found something that might be fitting for my purposes.
Finally, here are the sounds I’ve made, along with my collection from the above sites: