   opensource game engine
  please anyone interduce several opensource game engine with good supprt by designer team.   
  All purpose game engineshttp://www.panda3d.org/ (check this before all else)http://www.cafu.de/ (looks a bit weak)ID tech forkshttp://xreal-project.net/http://icculus.org/twilight/darkplaces/Cube 2 forks:http://sauerbraten.org/ (cube 2 itself)http://www.bloodfrontier.com/http://sandboxgamemaker.com/ ("kid friendly")http://www.syntensity.com/ (also check this)As for support all above engines are stable and if your into serious coding you support yourself with your own codeBut if your into more of a "scripting" approach check panda3d and syntensity as they use scripting languages and have a community around helping startups(in case of syntensity the IRC channel)You also have sandbox but I think its a bit to limited without forkingIf you want 2d engines I can post some too   