it will not change your way of creating game, i would name it fallout 1 & 2 way.
but i need to know, why do you want to make it in JME and what you want to leave 2d and what to make 3d?
because you can easly mix 2d with 3d.
Also this is the same for the character movement.
long time ago, i had a game with prerendered character images to use them for animations, like it is in fallout 1 & 2 games.
but it would be better for you just to use 3d model here. really. i know it could partially change your game.
if you really want to make it in fallout way, you could use:
but don;t know if it still work.
you can make it in shader, but you will need to learn shaders, so this idea is bad here. you just need to make it like we said.
about logIn background animation, you need to make like we said.
first read this:
then you need to know you have 2 types of Scene Graph(https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:scenegraph_for_dummies).
rootNode and GuiNode
where rootNode should be for your objects and GuiNode use for GUI elements like you need here.
about animating this, you need to use for example HUD Image or simple Quad and change it's material texture to another.
in that way you will make something like gif animation. it would be good for you to cashe animation first.
I cannot really change to 3d as i do not have the 3d images nor can i pay 100’s of pounds for a 1000 image library of 3d models, because it would mean recreating all the armours etc… The reason for my using the jme is its currently coded in Delphi therefore very restricted in my opinion therefore i have learn’t up Java to be able to translate and change it across.