Hey James, that game looks cool. I was a big fan of Dungeon Master by FTL in the day (and other first person crawlers like the Eye of the Beholder series).
I'm happy for you to use the Heroes of Adventure system (rules/wordings) as a basis for your creation as permitted by the creative commons licence.
All I would like is a credit for the game somewhere (i.e. words to the effect of 'rules based on Heroes of Adventure role-playing game by The Nameless Designer' for example). Happy for you to add a link to the game page aswell.
Good luck with the project and please let us know if it ever gets released to the public.