<<I've uploaded these to the web archive as well: https://archive.org/details/crush-40-open-your-heart-original-dc-version>>
These are early/demo versions of Open Your Heart by Crush 40.
Kenichi Tokoi on vocals:
The song was thankfully downloaded by someone before the Jun Senoue forums closed. This is an incredibly early version with Kenichi Tokoi singing. In the comments, someone did their best to piece together the lyrics. Lyrics included in follow-up post.
Open your heart (demo version, aug 22 1998):
As far as I know, this version is from the original announcement of Sonic Adventure, with Eizo Sakamoto's vocals, Hirotsugu Homma playing the drums, and Naoto Shiba doing bass--all members from Anthem. The lyrics for this one are the same as the final version of Open Your Heart.
Japanese prototype:
This version has slightly different drums and some vocals are a bit different. The biggest change is that the song is sung by a native Japanese person (that does his best, but isn't very fluent in English I think), therefore the English sounds like a mix of both. Engrish, if you will. This was also sung by Eizo Sakamoto. The lyrics are also the same as the final version.
Original DC version:
((NOTE: THIS SONG HAS TO BE UPLOADED IN THE NEXT POST)
This is the original dreamcast version. Now, I haven't played the original Sonic Adventure, but judging from the information I could find, Sonic Adventure DX: Director's Cut changed Open Your Heart a bit. I am not sure on this, so take that with a grain of salt. The lyrics are slightly different, so lyrics on the follow up post will be included.
March '98 Eizo Sakamoto ver:
This version is a bit earlier than the used to announce the game. Someone on youtube paid money (although they couldn't specify how much) to get this version from SEGA. This comes from the vaults of Jun Senoue. It is also sung in Engrish by Eizo Sakamoto. The lyrics seem to be the same as the final product.
That's all I have for this. I will update this if need be.