I'm curious what people are using to develop games for the Windows Phone (or XNA in general). I have come across a few engines but for the most part they don't seem to be actively maintained. If you are using an engine which you think does the job well please recommend it below.
FlatRedBall is an actively maintained XNA-based (MDX version still exists but isn't maintained I think) 2.5D engine that supports Windows Phone 7 as well as XNA PC and XNA Xbox 360 (and it's also simple to integrate with Farseer).
I kind of agree with coderanger. For all those specific examples you gave him, microsoft provides samples on their site. Full working state management, collision detection, animation. I know you want something put together but since you haven't received an answer you like, you could always take the game state project http://create.msdn.com/en-US/education/catalog/sample/game_state_management and pull some of the other samples together. All the code works fine. Again if someone provides you with an answer you like then ignore but it really won't take long to do what I am suggesting.
I've asked similar question on App Hub.
The answer was that there is only limited number of possible solutions, like Helium (helium.codeplex.com/) or Farseer Physics Engine ( farseerphysics.codeplex.com/) But, yes, they are not advanced enough yet.
Torque engine (torquepowered.com/) is coming somewhere in the future.
You might try Jemgine, it doesn't technically run on WP7 but only because of a few simple shaders that could be replaced with BasicEffect.