Hi…
For a game which is (other than cut-scenes and some minor ingame scenes) pretty much pseudo-3d, how can i use a primitive in the engine (eg a cube) and then have it be replaced by an animated character tied to the primitive in the game?
Image from the game camera, of the environment where the animated character would be moving (one room) :
Maybe this is what you mean?
This is a really old project of mine. The fore ground pieces were cut out and added as .png planes so you can walk behind them. The armature is parented to the cube, so the cube moves and there is a logic brick linked to the character so the animation plays when the character moves.
Awesome, thank you! 
If that’s what you’re looking for here’s a little ore info:
So you have to make the collision boxes to fit your scene and make them invisible.
Use a single plane to display the background.
Choose things that the character can walk behind, cut them out in image editing program (I use the GIMP) and make them new images.
Make sure each layer you create has the same dimensions as the background image.
Put each layer on a new plane and place it so that your characters can walk behind it.
You could probably find a more complex way of doing this, there are techniques for parallax or moving cameras, but the simplest (though maybe not quickest) way is just to use layers.
Like this:
Notice that I’ve darkened the area in the background which will be featured as a layer. This will help to show the player where they can walk behind, and bring out the foreground layer a little. I just used GIMP’s “drop shadow” effect for that.
The biggest problem is guessing where the camera needs to be in each scene and matching the “invisible” collision boxes to the position of objects in the scene. There’s not really any easy way to do that. It just takes trial and error.
If you find this method takes too much time you could try and google some tools for doing this automatically. Try researching camera tracking or motion tracking (though your scenes are static, they could use similar methods).
^Thanks…
I use Gimp for loads of stuff (including making the first avi file of parts of the cinematic) as well as altering images, and have just started to familiarise myself with Layers.
Wondering if there is some way it can be done more from ‘inside Blender’ itself, though…
Eg here are three rooms of the wip horror adventure game, which although can be loaded as layers as you said, maybe could work faster/more directly with some built-in Blender mechanism? 
