The Cave is at its heart a puzzle-platformer, albeit one narrated by a sentient cave.
At the beginning of the game, the player selects three characters out of a total of seven.
These characters are as follows:
Each character descends into the bowels of The Cave in search of their heart's desire -- which varies wildly depending on the character. How they attain their respective desires usually involves some fairly unethical behaviour.
The cave consists of several general levels -- levels that all characters must play through in order to complete the game -- and various unique levels specific to each character. Depending on which characters the player selects, certain unique levels won't be accessible during the course of the game (if you don't select the Adventurer, you won't get to play through the Pyramid. If you don't select the Knight, you won't get to play through the Castle. And so on...). However, because the levels of the cave are inter-connected, the player's characters may pass through portions of these levels nonetheless.
The player must traverse the depths of The Cave, solving puzzles, navigating platforms and in doing so discovering a little about each characters sordid history of greed, skulduggery and murder. Puzzles are solved in the traditional Ron Gilbert style -- finding useful objects and using those objects with other objects, or interactive parts of the environment. Many puzzles can only be solved by using all three characters together.
Whenever a character dies (by being impaled on spikes, electrocuted by a water-logged fuse box or incinerated by a dragon), they respawn a short distance away from the location of their demise.
At game's end, the player learns the fate of their morally bankrupt anti-heroes -- and hopefully a little something about themselves.