The bonus stage is progressing, I think it will have a unique style to it, while reminding people of the classic arcade Shinobi bonus stage. There will still be big differences,
I think, I am not sure, but I think the Shinobi bonus stage was so good because Sega might have wanted to create an arcade cabinet just around the bonus stage. Maybe they started the bonus stage as a game on itslef and this is the reason it is so much better than all the bonus stages that came in other Shinobis afterwards...
And after they decided to not release this arcade cabinet and instead added the bonus stage project inside the Shinobi game one...
This is just pure speculation, most probably false. Just my personal opinion on it.
The thief character will be started also too this week.
About the music, I received the 4th Shadow Gangs track, and it is great.
I'll post it for download when I receive a more polished version, probably before the end of this week.