Transport Fever - Transport Fever is an Adventure-based, Management, Strategy, Economy, Sandbox, City-Building and Single-player video game developed by Urban Games and published by Gambitious Digital Entertainment.
ANNO - ANNO is a city-building and economic simulation video game series, with real-time strategy elements.
Simutrans - Simutrans is an open-source transport simulator.
Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.
OpenTTD - An open-source clone of the classic game ...
The Settlers Online - The Settlers is a free web browser based strategy game along with a gameplay that drops anywhere between Age of Empires and the online strategy style.