There's another Blockade game not archived in Atarimania, which appeared at Computer Kontakt magazine (Issue Aug/Sept. 1985) by Marco Feikert, pages 68-69. It can be found here:
ATR image: http://atarionline.pl/v01/kazip.php?ct=kazip&sub=B&title=+Blockade+%28v2%29&file=Blockade.atr
BAS image: http://atarionline.pl/v01/kazip.php?ct=kazip&sub=B&title=+Blockade+%28v2%29&file=Blockade.bas |