Thanks, glad you enjoyed it!
Re getting into the enemy castle, I'll leave some tips here for anyone reading this:
> Talk to the old man who lives in the tree, he knows the secret entrance!
> The in-game level map (Escape, then option 1) shows only ladders and solid tiles, so fake walls/floors are visible as tiny gaps.
> Cheat code HHCAAQSS (Option 3 from the intro menu, then enter the code) will start you inside the enemy castle with a fine set of powerups!