OpenTTD is an open source clone of the Microprose game "Transport Tycoon Deluxe", a popular game originally written by Chris Sawyer. It attempts to mimic the original game as closely as possible while extending it with new features.

OpenTTD is licensed under the GNU General Public License version 2.0. For more information, see the file COPYING included with every release and source download of the game. OpenTTD is modelled after the original Transport Tycoon game by Chris Sawyer and enhances the game experience dramatically. Many features were inspired by TTDPatch

Significant enhancements from the original game include for example:
1. bigger maps (up to 64 times in size)
2. stable multiplayer mode for up to 255 players in 15 companies or as spectators
3. dedicated server mode and an in-game console for administration
4. new pathfinding algorithms that makes vehicles go where you want them to
5. autorail/-road build tool, improved terraforming
6. canals, shiplifts, aqueduct
7. larger, non-uniform stations and the ability to join them together
8. mammoth and multi-headed trains
9. clone, autoreplace and autoupdate vehicles
10. possibility to build on slopes and coasts
11. advanced/conditional orders, share and copy orders
12. longer and higher bridges including new ones, full flexible tracks/roads under bridge
13. reworked airport system with many more airports/heliports (i.e. international and metropolitan)
14. presignals, semaphores, path based signalling
15. support for TTDPatch newgrf features
16. drive-through road stops for articulated road vehicles and trams
17. multiple trees on one tile
18. bribe the town authority
19. many configuration settings to tune the game to your liking
20. save games with zlib compression for smaller sizes which does not interrupt gameplay
21. big support for internationalisation. OpenTTD is already translated into more than 40 languages
22. dynamically created town-names in 18 languages and newgrf support

Lots of effort has been put into giving OpenTTD a better usability. These include:
1. convert rail tool (to e-rail, monorail, and maglev)
2. drag&drop support for almost all tools (demolition, road/rail building/removing, stations, scenario editor...)
3. sorting of most lists based on various criteria (vehicle, station, town, industries, etc.)
4. mouse wheel support (scroll menus, zoom in/out)
5. autoscroll when the mouse is near the edge of the screen/window
6. sell whole train by dragging it to the dynamite trashcan
7. cost estimation with the 'shift' key
8. advanced options configuration window, change settings from within the game

Graphical/interface features:
1. screenshots can be in BMP, PNG or PCX format (select in game options menu)
2. more currencies (including Euro introduction in 2002)
3. extra viewports to view more parts of the gamefield at the same time
4. resolution and refresh rate selection for fullscreen mode
5. colourful newspaper after a certain date
6. colour coded vehicle profits
7. game speed increase (through fast forward button or by pressing the TAB key)
8. snappy and sticky windows that always stay on top and neatly align themselves to other windows
9. more hotkeys for even less mouse-clicking
10. support for 32 bit graphics

OpenTTD is officially supported on the following operating systems.
* BSD, especially FreeBSD, NetBSD and OpenBSD
* Linux
* Mac OS X (10.3.9 - 10.5)
* OS/2
* Solaris
* Windows 95/98/ME/2000/XP/Vista/7
OpenTTD is officially supported on the following operating systems.

The license of this software is Free, you can free download and free use this puzzle game software.