Google is not the first company to offer an operating system to rival Microsoft and Apple.

In fact, there's a long history of defunct or ignored operating systems for Google to pick through.

We've collected just a few here.

Many of these operating systems were plenty innovative in their time.

Where they each ran into trouble was either struggling to sell to anybody other than a few early adopters, or failing to evolve as their businesses changed.

The scary thing for Google is that it has had that same problem with almost all of its products beyond search.