Game development bottleneck

So I've been developing a game concept for a while now. I've got a story, a questline, mechanics and content all planned out. Issue is, I have never done any coding or any game development at all. The game is set in the old west and first person, and due to the need to deform the ground and manipulate terrain it has to be capable of doing things like digging holes and gravel or digging long tunnels in the ground.

Given the work I've put into the development of everything other than actual game itself I really want to give it a go making it. Does anyone have any suggestions on programs or tools/education program's to learn the skills I would need to make a first pass at something like this? Unfortunately no one I know has these skills so a team up isn't an option. Thanks in advance!

Note: the game is expansive in the fact there are hunting, digging, traveling and combat mechanics all required. I have had a go creating terrain in unity but realised very quickly I will need an expansive skillset to give this a go.