I cannot compare any games on console as I don't have any (I play on PC)
I see no problems using the tilt/leaning features of the wiimote combined with the buttons
in an FPS it could be mapped like:
tilt forward - walk forward
tilt backwards - walk backwards
tilt right - strafe right
tilt left - strafe left
Combine this with a function or use button (i write FN from now on)
FN + tilt right - lean right
FN + tilt left - lean left
FN + tilt forward - jump forward
FN + tilt backwards - jump backwards
and so on...
Like I mention above - I have no clue if this is existing in games already...
A simple prototype game can be set up quite easily in Papervision/actionscript
OOP Game programming in Actionscript is also quite easy - If you know basic programming that is...
To get started in Actionscript you can visit
http://www.gotoandplay.it/ for lots of tutorials.
And there are a few samples connecting Wiimote with Flashlib that is used in Papervision.
If you know about Papervision you also know that it is easy to import real 3d objects from 3d-programs like Blender and 3dstudioMax and so on...
The 3d models can then be used as main character in your game...
Just a few thoughts...
//UndCon