A couple of years ago, activity in Tango dried out without this really being explained in any manner. As early as spring 2009, I was dead tired of circumstances in the D community, its governance and so on, and although I loved the language (D v1 that is), I was uncertain of the future. I chatted off record with others, and it turned out I was far from alone. Kris was in a similar situation, but also had work drop truckloads on him.
Early summer that year, the main LDC devs started to write a new D compiler, more joined and soon we had a need to "fix" things. With a baseline of D1, some features were removed and some added, with more in the pipeline. This wasn't going to be D, and we found a new name. Maybe not original, but pretty.
Since we were writing the compiler in D using Tango, keeping Tango going was still a priority, but life happened. I and several others had kids (in my case a second), there were graduations, new jobs, and so on, and Tango suffered, and eventually also our new compiler suffered in terms of progress.
We had planned to open and release when we got to beta quality, and was on schedule to do that in less than a year. 3 and half years later, and we're maybe at alpha quality. But there is still activity, and when we now open up, maybe others will be interested to take a look.
What does this mean for Tango? Tango will play a role in this new language, whereas Tango for D1 is there to take really. If someone wants to continue it where it stands, they are welcome to do so. There is a D2 fork on github, and I believe it works.