Thunder Castle - an arduous journey to Level 15 in Intellivision / Aquarius Posted May 10, 2019 · Edited May 10, 2019 by Shad0WeN Checked it. It's actually signed by both of them That's awesome! I am jealous lol. Did you know the art used on the front cover wasn't even created for Thunder Castle? It believe it was meant as a promotional piece for Advanced Dungeons and Dragons: Treasure of Tarmin but supposedly was never used, so when INTV Corp. published Thunder Castle it was 'recycled' and became the box art. It makes sense since other than the dragon none of those creatures appear in the game.