an interesting start, so this is what you can do to work on making it a great game. have it start out that you get trapped in a cave because the entrance got block by a cascade of boulder due to an earthquake or something.
You have some items in your pocket that you can take out and use, like a knife and a lighter. So you use the lighter to create a small glow, but you still need more items that would help you while you try to find an exit. Make it so you can gather things that you see. Have a stick and a rag, and you burn the rag to make a torch to creat more glow to see.
And probably have a hidden mystery in the cave that you come across. Some exploring team got lost in the cave a long time ago and you find a skeleton. You use thier tools and stuff to help your way, like a map and maybe a weapon of some sort. Add hazards to challenger the gamer. Crossing a dangerous underground river or snakes.
And work on detail to make it look like what you looking at is easily identifiable. Some ideas to help you out. It's like a point and click game and I hope this helps you out.