No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. Reviews and prices only.

OpenTTD

Transport Tycoon Deluxe is required to add OpenTTD to your library. OpenTTD is a business simulation game in which players earn money by transporting passengers and cargo via road, rail, water, and air. It is an open-source remake and expansion of the 1995 Chris Sawyer video game Transport Tycoon Deluxe. Build Connect industries and cities on procedurally-generated maps of up to 4096 x 4096 tiles by building a network of roads, railways, docks, and airports. Navigate dense city streets, cross oceans and rivers, and conquer high mountains in one of four climates. Transport Work alone or with friends to complete production chains and transport finished goods to towns. Assemble a fleet of hundreds of vehicles, transferring cargo as needed in an interconnected, multimodal network with optional cargo destinations. Upgrade Keep up with technological improvements through the years as towns grow; new modes of transport are invented; and industries appear, change production, or fail. Expand stations and build network capacity to keep up with demand and avoid delays. Extend Customize your OpenTTD experience via community-made mods downloaded through an in-game content service, including real-world vehicles, new industry sets, custom scenarios, and more. Free and open-source OpenTTD is free and open-source software, licensed under the GNU General Public License version 2.0. OpenTTD is under ongoing development. OpenTTD is not an abbreviation of anything.