... let's add mechanics to the discussion.
Well, I've put my two cents in regarding the mechanics. Right now I see two different game possibilities that both look like they'd work pretty well... my description and Doho's. Either with some modification I'm sure... which is what this discussion is for.
For example, in Doho's suggestion (which I am calling Tourist Trap for lack of anything better) he mentions scoring rounds and scoring for various special features. I dont' know exactly how that would work. With a little pondering today I looked at possible tile configurations with each side being either Rock, Open, or Passage. I looked at the various features a cave system could have- completed caverns connected by passages, completed (i.e. fully surrounded by open space) Rock features, Stalagmites/tites and underground springs
OK... I'll put in my two drachmas here too...
First... don't refine your topic too much... "Spellunking" should be a game wherein ALL of the definitive topics can be covered (and, btw, LoTR is NOT public domain).
jwarrend has it right. Make this a resource management game where each player "shops" for his materials to go spellunking with... and force some hard decisions to be made.
The game now revolves around both "having brought the right stuff", and using "the right stuff properly" from a strategic/tactical sense in the game. In a player v.game model, this can mean simply a random events phase within the 'caves, mines, or ancient architecural digs site chart' and in a player v. player, it can also mean sabotaging the alternate paths to the goal. Scoring can be made simple in all three cases by offering money for exploration acheived, which could then be used to purchase further equipment and allow further exploration, etc... with game end being determined by either death of the exploring party, or retirement due to hefty profits from said exploration.
...and now you have an "Explorers Game" that will cover the needs of a much wider market of players... hence 'more sales' :-).
...yes... I know how to allow the mechanics the flexibility to work under this scheme as well... allow a self-generating board, perhaps drawn on graph paper by the players... with differing charts for both random map generation and random occurrences... for each type of exploration you wish the game to cover.
...I'll shut up now and read some more :-).
XXOOCC