Sploder doesn't seem to work for you. Stencyl's been over-used, and the games most people have submited have been tutorials or tutorial+'s and so they don't do well. Unity makes great graphics, but again, the games are basically something made in a tutorial, plus a few trees, and then they get submitted. Plus, support for Unity is sketchy, and sometimes it won't play anymore. However, try Flixel. Flixel seems to work well, the games produced have been good and well received, and Flixel's free to download. :)
Exedor
Sploder doesn't seem to work for you. Stencyl's been over-used, and the games most people have submited have been tutorials or tutorial+'s and so they don't do well. Unity makes great graphics, but again, the games are basically something made in a tutorial, plus a few trees, and then they get submitted. Plus, support for Unity is sketchy, and sometimes it won't play anymore. However, try Flixel. Flixel seems to work well, the games produced have been good and well received, and Flixel's free to download. :)
http://www.newgrounds.com/wiki/creator-resources/game-dev-resources