Apparently there is a secret part. You must watch it to the end, wait for the endscroller to finish, then type 'PRECALCULATE'. HD installable with patch.
Reviewed and voted 2nd best demo of 1991 in R.A.W 2 (february 1992). The magazine also featured a long interview with PGCS detailing the making of the demo. Voted #3 best trackmo in The Charts 1 (febuary 1993).