Our game, ATOM A Post Nuclear RPG spent a really long time in the hellish planning stage. The main reason for it was, that we were trying to use our own custom game engines built from the ground up. Now we realize that it was a mistake. Everything took too long to create. The lack of support made us investigate each problem on our lonesome. It wasn't until we transferred all our trust into Unity, that we became capable of making our first playable build. Since that time, we found that we could concentrate on making the game itself, without worrying about making new engine features. And this is the main thing any developer needs, if you think about it. A friendly and capable environment for creating his world.
Now, in less than a year of working during our free time, we managed to create a full fledged demo build from scratch. It is currently getting greenlit on the Steam Greenlight platform.