if you like simulation or sandbox games you will love this

The demo comes with the whole planet Earth that can be explored in a free-camera mode or in a 8-wheeler truck. People who like it and/or want to support us and the development of Outerra engine can buy the alpha release of Anteworld at a discounted price ($15), half the amount for the final release. Doing so will give you access to regularly released alpha/beta updates of the game, together with the final version when it's done. The price will gradually rise with each major release. You will also become our beta-testers, with ability to influence the priorities of the development.
The full game includes also a plane and a helicopter, and basic sandbox tools that allow you to create roads and runways and place stock objects. A model importer and vehicle configurator that will allow creating custom models and vehicles will be coming soon in an update to the game.

This alpha release features:

• A complete, real scale planet Earth that can be explored
• Created from real elevation data with resolution 90m where available, 1km resolution for oceans; data are dynamically downloaded as you go
• Further refined by fractal-based procedural techniques down to centimeter-level details
• Vector-based road system that integrates with the procedurally generated terrain
• Ability to place static stock objects and drive provided vehicles

http://www.outerra.com/