Unciv

Unciv is a civilization-building strategy game about developing a society across a map. Expand cities, choose technologies to research and decide how to deal with competing powers. Progress in one area can support another, making the order of your investments an important part of planning.

It offers single-player and multiplayer play, with offline play available for solo sessions. The Android game is free and has no ads. Its open-source project also gives interested players a way to follow development and contribute translations.