Subterrain: Mines of Titan

Funnily enough, 'Natural' is considered more difficult than 'Player Progression' when I found it easier to proceed on the 'Natural' type because I could rapidly descend and acquire the research and equipment needed before the enemies became too much of a problem.

You will find that the combat is exciting, the exploration is interesting

-World Building: The moon 'Titan' is a unique setting and the opening premise behind the story is interesting.

(Oh, and the game's visuals are nice, equipped items show up on your character's sprite, and I ran into no bugs whatsoever, so Subterrain: Mines of Titan is pretty well done overall.)

Environmental sound effects such as distant machinery, echoing footsteps, and the unsettling noises of creatures lurking in nearby tunnels help build suspense.