The first steps of the project were 5 years ago. But we didn't really start getting going until about 4 years ago, and using the Torque Game Engine Advanced at the time. When Hero and Bigworld became available 2 years ago (we licensed it when they first started the $5k indie license, before scrapping that for the free license) we picked it up a couple weeks after it became available. So that would have been just over two years ago. We didn't really start serious work on the port though until October of that year.
So basically figure about 2 years of Hero Engine so far. But we did have a lot of art and design assets already completed they just needed porting/re-exporting for Hero Engine. We're expecting one more year of development time before launching mid to late next year.
Other information that may be relevant. We have had a team of 5-15 people, with under 10 developers for most of the game's lifespan. We had a core of 5 people (2 programmers, 2 3d artists, 1 2d artist) for most of it, before ramping up to include some additional faces in the past 6 months. All of us work day jobs and are moonlighting. If we had a full time team we could have certainly gotten things done more quickly.
