Time to list the still or mostly unrevealed BG myths (at least the ones i know)
1) Orchestra Project
First mentioned in fan magazine 1996 (?)
Status: in work, coming soon (recordings 10/11 done)
Details: Forum Thread: Blind Guardian's 11th studio album - THE ORCHESTRAL PROJECT
2) Documentation "Travellers at the edge of time"
First mentioned: March 2011
Details: News site
Status: unknown, even Hansi answered that he has no clue about it.
Personal Prediction: will never be released
3) Beyond the Red Mirror Comic adaption
First mentioned: June 2015 on Felipe Marchado's Facebook site
Status: First 12 pages were available for preview at Comic Con San Diego 2015, CANCELLED (November 2017 by Felipe Marchado Franco)

4)Silmarillion EP
First mentioned in BG fan club magazine
Status: cancelled, Songs 'Doom', 'Tides of War', 'Harvest of Sorrow' got meanwhile released
Any other myths, besides Andre is a hologram or Marcus giving skateboard riding lessons?
Feel free to correct, add, criticize....