OpenTTD is an open source clone of the Microprose game "Transport Tycoon Deluxe", a popular game originally written by Chris Sawyer.
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FlightGear is a free flight simulator project.
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Simutrans is a free and open-source transportation simulation game.
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OpenCity is a full 3D city simulator game project.
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Sweet Home 3D is a free interior design application that helps you place your furniture on a house 2D plan, with a 3D preview.
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Vega Strike is an Open Source 3D Action-Space-Sim that lets you trade, fight, and explore in a vast universe.
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Danger from the Deep (known as dangerdeep or DftD) is a free (as in free speech), Open Source World War II german submarine simulator.
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Rigs of Rods (also known as RoR), is an Open Source truck, car, airplane and boat simulator.
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