Simutrans

This is a strategy game where you must manage the development of a city, paying special attention to good transportation and economic progress of your city.

This is a game with some amazing graphics quality, taking into account that is free. The level of detail is not excessive, allowing it to run on slow machines without problem. The entire interface is controlled by mouse, so you just have a learning curve, and of course, its support for multiple languages, including Spanish, helps.

Your goal will be to manage the city, causing companies to develop their work through the use of raw materials. These materials must be transported (hence the importance of good communication system), as well as passengers, mail and other goods. This, of course, care for the environment.