Cytopia

Cytopia is a city building game with isometric retro-styled pixel art and a focus on mods. Lately it has moved from a promising engine to a promising game. There is already support for a custom UI system, terrain manipulation, roads and water, buildings and much more. The pixel art looks great and many cool features are planned for the future such as procedural terrain generation, OpenGL rendering and a scripting language for mods. Also, it seems like the project is currently looking for more developers, if you happen to be interested.

Buildings, roads and hills in Cytopia.