This really sounds good. I had heard the tracks on bandcamp before seeing them "in action" on youtube, and I have to say it all fits together better when you can see the game being played along with the music. Great job.
I like some remixes like Spark Man's and Top Man's, but there is some I really didn't like as they completely change the style of the song, such as Hard Man's or Gemini Man's.
Is this a rom-hack ? If so, the work to completely replace the music engine while keeping the sound effects intact should have been extremely hard.
What exactly is Bandcamp's policy on posting covers? I know they make a statement that says you must be the owner of the intellectual property, but after seeing digital albums like this I've been tempted to start on my own chip arrangements.
If you want the right to sell your covers, there is a standard royalty rate. You can be automatically granted the right by paying the royalty (this is what I do for MOON8).
For services that sell your music for you, they don't generally do this for you. They don't police copyright. It's on you to secure the rights.
If you use a service like limelight, a 10 song cover album will the ~$200 for 100 download royalties. You'll need to sell about 20 albums to break even.
I may do this in the future. (I already have an artist & album in mind.) But for now I guess I'll see about finding public domain music. (only have one right now)