Active Forums is alive and well.  Actually its about a week away from a major update involving another user interface upgrade.  IMO it is the best available for DNN but I'm a bit biased.  We have many things working in the pipeline right now too including native support for Tapatalk hopefully within the next month or two.  

Most important thing is that it is actually being developed.  Sometimes what is shown to the public isn't always all that is going on, there are a few of us working behind the scenes to keep it alive.  You can find the module at https://github.com/activeforums/activeforums and the official website is activeforums.org (github has far more info than the website).  

Hope this helps!