I believe the perfect ios game would be HOI4: The tech/national focus, all that would work perfectly, the only real problem, would be the actual battling, which I think I have a souliton too. Instead of focusing on micro managing focus more in the battle plans on the whole. You could make the game 2d but just dont make it one of those moving each unit in heaxgons kinda game. But most importantly, make the controls simple and fluent, and the game easy to pick up for a quick fix. Remember, we only use IOS when away from home, so there needs to be features like, when you close the game it auto saves, so you can just pick it back up and continue. Remove no features! Just make the controls simple and not frustrating...