Exactly what any D&D 5E game needs. I've been bootstrapping the previous Index Card RPG in my 5E games even without the core rule set, and it's a huge force multiplier for the GM/DM, without requiring ornate battle maps or terrain. I'm off the belief that nothing you can build will ever be more amazing than your player's imagination. Give them enough to visualize in order to make important and tactical decisions, and that's it.

Absolutely going to slowly work in the "effort" system as well!