I liked greenfoot mainly for

• graphical support
• collision detection
• input handling

But more I have been doing more advanced things for which greenfoot isn't as good. So are there any good alternatives? I definitely want:

• graphical support
• collision detection (preferably even polygon collides)
• a better IDEA

And I would like:

• networking support
• 3D and full screen support
• input handling

I'm probably willing to learn a new language. But I don't want something that has a big complex interface (like Unity). I still want control over basic things (like movement). any suggestions?