The problem with that game was that the basic rules sucked. My brother started adding extra monsters to the dungeons and it *still* didn't make it any harder once I had the 'Gattling Team' set up: the three guys carrying crossbows and heaviest armour would sit at the end of a corridor, then the little guy would just open the door and run away while the big guys mowed 'em all down.
You can only solve this with more advanced rules:
(a) 'surprise' penalty, each new monster seen removes 1 from your current move
(b) time limit where the hereos have, say, 50-60 turns to exit the dungeon before the enemy 're-enforcements' automatically overwhelm them, perhaps with a 50% bonus cash for doing it in 30 turns or less
(c) each use of a ranged weapon requires a 'pass' turn to reload it
(d) activated monsters can sneak around the back, activating other monsters as they go, and creating up to two additional secret doors not on the original map
(e) allow activated monsters to run away to 'arm themselves' with a single shot ranged weapon if two or more ranged shots were fired at them from beyond their move limit
.. and so on. Adding more health to the monsters wasn't really a good idea for a dice based game, but making the monsters use tactics to try and thwart the hereo's tactics makes the players have to act more realistically.
On the flip side, once you know the game really well it is a piece of cake to make your own "travel version" by hacking up one of those $2 magnetic chess sets.