We must rip this.

[Goemar]

I know it's not M.U.G.E.N but I think the rules still applies as they are basically somebody else's work.
Sprite ethics in full force here I guess.

Now if you could somehow contact the people or team responsible for the game and get there permission to archive them I guess all is good, but I doubt that is possible. Maybe just mentioning the game on an update and the fact it contains all the sprites will have to do here.