OpenTTD v1.11.0 beta1 is released. OpenTTD is an open source simulation game based upon the popular Microprose game "Transport Tycoon Deluxe", written by Chris Sawyer. It attempts to mimic the original game as closely as possible while extending it with new features.

Features
OpenTTD is modelled after the original Transport Tycoon game by Chris Sawyer and enhances the game experience dramatically. Many features were inspired by TTDPatch while others are original.

Significant enhancements from the original game include:
bigger maps (up to 64 times in size)
stable multiplayer mode for up to 255 players in 15 companies, or as spectators
dedicated server mode and an in-game console for administration
IPv6 and IPv4 support for all communication of the client and server
in game downloading of AIs, NewGRFs, scenarios and heightmaps
new pathfinding algorithms that makes vehicles go where you want them to
autorail/-road build tool, improved terraforming
canals, shiplifts, aqueducts
larger, non-uniform stations and the ability to join them together
mammoth and multi-headed trains
different configurable models for acceleration of vehicles
clone, autoreplace and autoupdate vehicles
the possibility to build on slopes and coasts
advanced/conditional orders, share and copy orders
longer and higher bridges including several new designs, plus fully flexible tracks/roads under bridges
reworked airport system with many more airports/heliports (e.g. international and metropolitan)
presignals, semaphores, path based signalling
support for TTDPatch NewGRF features offering many options for graphics and behaviour configuration/modification
drive-through road stops for articulated road vehicles and trams
multiple trees on one tile
bribe the town authority
many configuration settings to tune the game to your liking
save games using zlib compression for smaller sizes, while not interrupting gameplay
significant internationalisation support. OpenTTD has already been translated into over 50 languages
dynamically created town names in 18 languages, plus NewGRF support for additional languages
freely distributable graphics, sounds and music
framework for custom (user) written AIs
zooming further out in the normal view and zooming out in the small map
Lots of effort has been put into making OpenTTD easy to use. These include:

convert rail tool (to electrified rail, monorail, and maglev)
drag&drop support for almost all tools (demolition, road/rail building/removing, stations, scenario editor, etc)
sorting of most lists based on various criteria (vehicle, station, town, industries, etc.)
mouse wheel support (scroll menus, zoom in/out)
autoscroll when the mouse is near the edge of the screen/window
sell whole train by dragging it to the dynamite trashcan
cost estimation with the 'shift' key
advanced options configuration window, change settings from within the game
Graphical/interface features:

screenshots can be in BMP, PNG or PCX format (select in game options menu)
more currencies (including Euro introduction in 2002)
extra viewports to view more parts of the game world at the same time
resolution and refresh rate selection for fullscreen mode
colourful newspaper after a certain date
colour coded vehicle profits
game speed increase (through fast forward button or by pressing the TAB key)
snappy and sticky windows that always stay on top and neatly align themselves to other windows
more hotkeys for even less mouse-clicking
support for 32 bit graphics
support for right-to-left languages
support for other (sized) fonts where the user interface scales based on the font and translation

OpenTTD Changelog:
Feature: [GS] Ability to set some extra text in the industry window (#8576)
Feature: Show rainforest under vegetation on smallmap (#8562)
Feature: Automatically determine window size on new install (#8536)
Feature: Towns can build tunnels (#8473)
Feature: Make maximum length of town bridges depend on population (with a minimum limit of 4) (#8439)
Feature: New icons for renaming and go-to-location on GUI windows, and improve consistency of usage (#8455)
Feature: Support for ARM64 on Apple Silicon and Windows (#8340, #8577, #8583)
Feature: Add an option to disable tree growth completely (#8415)
Feature: Support for Emscripten (play-OpenTTD-in-the-browser!) (#8355)
Feature: Show group name as part of the default vehicle name (#8307)
Feature: "Frozen" economy setting that stops production changes and industry closures (#8282)
Feature: New velocity unit "tiles/day" (#8278)
Feature: Option to automatically remove signals when placing rail (#8274)
Feature: Increase max possible distance from border for oil refineries and rigs (#8237)
Feature: Improve tree planting window, and allow planting 'clumps' of trees by dragging in the scenario editor (#8234)
Feature: Indian Rupee (INR) currency (#8136)
Feature: [GS] Ability to give a company exclusive access to an industry (#8115)
Feature: Hotkeys for Land Info window, News window & close error window (#8053, #8266)
Feature: Improve rendering of large viewports (#7962)
Feature: [GS] Influence industry production changes from GameScript (#7912)
Feature: [GS] Push-buttons on storybook pages (#7896)
Feature: Option to group vehicle lists by shared orders (#7028)
Feature: Drag-and-drop vehicles in group GUI for shared order groups (#7028)
Add: [GS] A tile parameter to GSCompany::ChangeBankBalance for showing changes more visually (#8573)
Add: [NewGRF] Allow NewGRF vehicles to query the current rail/road/tram type (#8554)
Add: [Script] ScriptCargo::GetName for the human readable name of cargoes (#8544)
Add: "reload" console command to reload the current scenario or heightmap (#8527)
Add: [NewGRF] Flag to test if inflation is on or off (#8427)
Add: [Script] Native priority queue (useful for things like pathfinders) (#8091)
Add: [NewGRF] Industry behaviour flag to override second cargo production clamping for water industries when using smooth economy (#8079)
Change: [SDL2] Start game on the screen where the cursor is (#8572)
Change: Use a dark background for all profit graphs to increase contrast (#8557)
Change: Reword warning in cheat window (#8538)
Change: Enable the toolbar for road/rail/dock/airport, regardless of vehicle availability (#8521)
Change: For arctic and tropical climates, make sure at least a few hills are generated (#8513)
Change: Destroying a tunnel/bridge now sells the tracks before destroying the tunnel/bridge (#8508)
Change: Move "give money" from client-list to company window (#8500)
Change: [MacOS] Hide Dock and menu when in fullscreen mode (#8487)
Change: Improve performance for complex vehicle chains by resolving sprites less frequently (#8485)
Change: Make engine reliability independent of introduction date (#8470)
Change: Some default settings to improve gameplay for new players - default non-stop orders on, disable inflation, quick goto orders, show track reservations, and more (#8463)
Change: Converting town-owned road types now requires a positive town rating (#8457)
Change: Rework server list buttons for searching LAN/internet servers (#8426)
Change: Add some styling to GS question windows depending on the type (#8422)
Change: [Linkgraph] Speed up game exit by allowing job threads to be aborted early (#8416)
Change: Prevent towns from building dead-end road bridges (#8401)
Change: Send network error to the server before making an emergency save (#8387)
Change: Extend the allowed range for max loan setting up to £2 billion (#8386)
Change: Don't display OS name when exiting the game (#8366)
Change: Save openttd.cfg immediately on changing a setting (#8358)
Change: Autorenew now defaults to on (#8352)
Change: [NewGRF] Also use aircraft property 12 for helicopters (#8347)
Change: Service at depot also resets breakdown chance (#8317)
Change: Use key names instead of characters in hotkey.cfg (#8291)
Change: Allow command cost-estimation while paused (#8222)
Change: Always apply inflation from 1920 to 2090, no matter the game start year (#7589)
Change: Use CMake for build system (#7270)
Change: [Linkgraph] Pause the game when linkgraph jobs lag (#7081)
Change: Place "Group by" above "Sort by" in station window for consistency (#7028)
Fix #8589: Prevent desyncs with vehicle motion counters and NewGRFs (#8591)
Fix #7670: Improve pathfinder performance when lost vehicles are blocked from moving (#8568)
Fix: Inform user if a custom font failed to load due to missing glyphs (#8559)
Fix: Don't allow wagon chains (without an engine) to exceed maximum train length (#8533)
Fix #7619: Super fast NewGRF aircraft could be unable to land (#8531)
Fix: Improve connection retries for the content server in cases of broken networking (#8530)
Fix #7972: Show invalid orders to stations that don't accept the vehicle (#8516)
Fix: Error when trying to clone a vehicle with invalid orders (#8515)
Fix #8050: Various off-by-one errors in how the end-year of the game was used (#8512)
Fix #8332: Aborting vehicle group drag & drop could cause crashes (#8511)
Fix #8168: Allow relocating HQ partially over an existing HQ (#8510)
Fix #8068: Allow selling tram track regardless of bank balance (#8509)
Fix #7604: Prevent houses from wandering away from roads (#8507)
Fix: Make the "password" button the same size as the other buttons in the Company window (#8500)
Fix #7611: Keep news about vehicle accidents around after the vehicle is cleaned up (#8497)
Fix: [MacOS] Full animation in fullscreen mode was reducing the height of the window (#8491)
Fix: [MacOS] Loading custom fonts (#8484)
Fix: Network client makes emergency saves twice if the server is disconnected (#8477)
Fix #8462: Stop towns from trying to build roads on water (#8471)
Fix: [NewGRF] GetCurveSpeedLimit should use the railtype from the current tile (#8466)
Fix #8437: Crash when using certain heliports with certain rotated airports (#8458)
Fix #8437: Planes would land at the wrong height if the top corner of the airport was lowered (#8458)
Fix #8297: Infrastructure counters for road tunnels, bridges & depots (#8454)
Fix #6468: Don't store the version of AIs that are started via console (#8430)
Fix: Don't lower tree density if spreading is not enabled (#8413)
Fix: Prevent savegame version conflicts with certain old patchpacks (#8411)
Fix: [NewGRF] Variable 0x44 was always HZB_TOWN_EDGE for road stops (#8400)
Fix #8313: Use correct capitalization for TTO / DOS music files in the baseset metadata (#8385)
Fix: [NewGRF] Action 7/9 conditions 0x0F to 0x12 failed, if 'param' was 0x88 (#8382)
Fix: Change the working-dir searchpath when using '-c' (#8367)
Fix: Useless warning with -snull and no BaseSounds available (#8361)
Fix: Crash trying to load TTO/TTD savegames. (#8356)
Fix: [Script] Don't echo script exceptions to console (#8331)
Fix: Slovak ownname was using the wrong form (#8326)
Fix #8311: [NewGRF] Industry probability at map generation was scaled differently when set via property or callback (#8312)
Fix: Only check houses for cargo when generating subsidies with towns (#8305)
Fix: Sprite preview in sprite aligner was too small with scaled UI (#8288)
Fix: Spell 'Viewport' consistently (#8260)
Fix #7772: Show vehicle destination on mouseover when vehicle stopped (#8236, #8543)
Fix #8232: Huge screenshot warning was shown incorrectly (#8224)
Fix #8153: Report incompatible cargo/order when autoreplace fails (#8169)
Fix: [Script] ScriptMarine::AreWaterTilesConnected did not work for aqueducts (#8074)
Fix #7645: Add cost of clearing the sloped tile to the price of a dock (#7947)
Fix #6452: Reset only editable and visible settings from GUI (#7890)
Fix: Original terrain generator did not keep a single gap of water at the borders (#7883)
Remove: In-game console command "content select all" (#8363)

http://www.openttd.org/

http://www.emucr.com/2021/01/openttd-v1110-beta1.html