Armory is missing axis constraints features
But i managed to make 2.5D physics in logic nodes ( it works with the stable release 2.79 ).
https://github.com/DevMagicLord/Godot3/blob/master/Armory/25D%20Physics.zip
It’s a small example but it should get you started to keep physic objects like player or projectile aligned into a 2.5D plane.
Some notes :
- Ground check raycast nodes frame and some variable on Jump nodes frame to avoid double jump are not connected, they was working but no more after.
- animations is not managed the best way like in code, calling PlayAction should be called only when there is a state change instead