N.B: Ardor3D != JogAmp's Ardor3D Continuation
dead != alive
P.S: JogAmp's Ardor3D Continuation is a general purpose 3D engine written in Java but it can be used in games (it's used in mine). It's actively maintained and developed but it's less active than JMonkeyEngine and its community is smaller. In my humble opinion, keep in mind that there are numerous members of community who blow hot air (i.e lots of people are very active on some forums but they aren't very helpful, they just talk) and more than 95% projects of games just end in the graveyard.