In terms of app based games...
I didn't really like how Descent: Legends of the Dark felt like a video game that happened to have some board game pieces associated with it.
X-com did it pretty well, but used real-time play to keep the game speedy.
This one, I think, really gets it right. The app basically handles all of the complex work of the enemies and events, while you handle your cards and whatnot yourself.
To do this without an app, you'd need a ton of decks of cards to randomize enemy behaviors and events.
Basically, like an event deck, a dungeon deck, a deck for each monster, a deck for each companion, a deck for each villain, etc.
It'd be a lot of card draws and such that really wouldn't have a lot of value.
The app just does a lot of virtual card draws for you. In fact, many of the things are actually conceptual virtual cards, keeping the game grounded as a board game.