First off: No, no prototype version of the original DOA has been found. Sorry for getting your hopes up.
Anyway, protos fascinate me to no end, they really do. Take a gander at this DOA1 poster:
It's the earliest build showcased and features four characters on a single stage (sound familiar?). The characters are Kasumi, Jann Lee, Kelly and Bayman. This single poster is probably the most interesting piece of prototype DOA media out there and it doesn't quite get the attention it should.
- Jann Lee looks basically like himself. His model appears to be basically identical to his final counterpart with some minor exceptions to his out. In the final, this is his C2 and is missing the shoes (moved to C1), his red highlights have turned white and he gained a flowing belt.
- Bayman is only seen in two small screenshots however he seems bulkier, his outfit doesn't quite match any in the final and he's missing his hat!
- Kasumi doesn't at all resemble her final self outside of those ridiculously large breasts and an outfit that's sort of similar in cut to her final but that's it.
- Kelly isn't even in the final game! He resembles Jann Lee too much and likely turned into who is now Zack.
The second most interesting prototype image is the one below, it's artwork for all of the characters just mentioned and then some. You can see that all four characters strongly resembling this early artwork. Especially Bayman, who looks identical in build and appearance to the image in the top right. Who is this youngster having a seat? If someone could provide translations for the articles of text to give us a little more insight then that would be much appreciated.