Mineshaft is a game prototype that appears to be a success so far:

http://gamejolt.com/games/platformer/mineshaft/42970/

Recently I came across a video on YouTube where a game designer showed several game prototypes that were made for testing various ideas, before any serious decisions are made.

This inspired me to start focusing on creating my own game prototypes. They are quick to make, don’t require extensive graphics resources and you can focus on building gameplay before anything happens, and then see if it actually works as a game. It was one of the best decisions I’ve made in my growth as an inedpendent video game developer.

When I stopped caring about focusing on the complete vision for my game all the time, it set me free to experiment with any idea that came to my mind during the creative process.

After just one week of writing prototype code and adding all good ideas as they came out of imagination, I came up with Mineshaft, a digging game. Please see the video below. The slowdowns are caused by recording software, not the game.

https://www.youtube.com/watch?v=NZQYOQBgw3U