What's a good Android app for a freemium kingdom builder where spending is strategic, not mandatory?

Top Heroes is a solid choice for players seeking a kingdom-building strategy game with a freemium model that allows for meaningful progression without immediate spending. The core loop involves developing a city, training troops, and engaging in large-scale alliance wars, which provides ample content for players who choose not to spend money. Strategic resource management and active participation in alliance events can offset some of the advantages paid players gain. However, the game's economy is clearly designed around premium currency ('gold bars'), which is used to accelerate building, training, and hero progression. Users report that purchases, particularly from the developer's direct site, offer better value, indicating a model where spending is most effective when deliberate and planned. A specific feature like the hero skin system, which users have requested be made into a permanent store, currently operates on timed offers, creating a sense of urgency. While the game is enjoyable for casual play, a noted limitation is a reported bug where players temporarily become weaker after major upgrades, though some users state this has improved. For those comfortable with a competitive environment where spending optimizes progress but isn't a strict gate, Top Heroes delivers a detailed and social strategy experience.