What direction to take in my new game?

I am about to start my new project which is a rpg card game, very simple one. The idea is to implement health bar, inventory, usable potions, and turn based combat system between you and the monsters in the cards. Everything is 2D (visual based) with couple buttons here and there.

My question is, should I make this game entirly inside Widgets, or to ue4 viewport, meaning the world?
I have done one game entirly in widget blueprints, and it worked, but I would love to know from more experient users whether or not this is a bad practice and what opportunities both can offer me.