Saves from Updates 2 and 3 are fully compatible with Update 4. However, due to various changes, existing factories may need to be updated.
All mods have to be recompiled and use the new mod manifest file.
Notable breaking changes
Some pre-existing docking areas might not be working if built near shallow waters.
New feature: Bridges
Introduced 2 types of bridges: truss and cable-stayed.
Bridges have a modular lane system that currently supports either roads or train tracks.
Bridges are constructed similarly to train tracks by placing a start point and dragging a bridge.
Bridges can be built in 8 cardinal directions, but can be connected to the terrain only in 4 directions.
Bridges are fully compatible with all tools, such as copy/paste and blueprints.
New feature: Amphibious vehicles
Added amphibious trucks and excavators that can traverse and work on water.
Unless assigned, amphibious trucks only take jobs that normal trucks fail to do.
Amphibious excavators can mine underwater to a depth of -5.
New feature: Pathfinding for ships
Ships now use pathfinding.
Docks can be built anywhere and will work as long as they have access to the map edge.
Added ships navigation overlay similar to vehicles.
Ships capacity was increased to compensate for longer travel times.
World mines capacity was increased as well.
New feature: Expandable stacker tower
Added stacker tower that allows dumping materials over a range of 20 tiles and a height of 15 tiles (both range and height are configurable).
Elevated rails can be attached to the tower to extend its range, with an option to auto-build them.
Maximum throughput is equal to two tier 3 conveyor belts (900 per minute).
New game mode: Sandbox
New games can now be started in a Sandbox mode that allows various options such as instant free-build, infinite electricity/maintenance, etc.
New source/sink entities that can be used in Sandbox and in regular games serve as read-only markers.
Sandbox can also be applied to existing games using the console command enable_sandbox.
Added a new sandbox-only flat map for quick testing and prototyping.
This mode is currently tailored for modders or players who wish to design optimized blueprints.
Additional new content
New map: Shattered Isles, the largest map in the game, with an area of 26 km^2.
Expanded and adjusted all the existing maps to allow for bridge building; maps are on average 15% larger now.
Added three tier 2 locomotives, three tier 2 wagons, and a tier 2 coal tender.
Added the waypoint train station.
New DLC: Trains Expansion
Electrified train tracks, train stations, and level crossings.
Five new locomotives: electric tier 1 and 2, gas turbine, fireless-steam, and nuclear.
New wagon and station module for molten materials.
Captain’s locomotive available for owners of both this and the Supporters Edition DLCs.
Quality of life improvements
Added machine and vehicle productivity statistics with monthly and yearly history.
Added search on map feature to the search menu (Ctrl+F), which allows easy search for machines, buildings, vehicles, and even their contents.
Buildings can now be placed over trees that are removed during construction.
Mining, Forestry, and all other tooling areas are now limited by surface area and not just the max edge size, allowing for the creation of larger non-rectangular shapes. All the areas have also been increased. Blueprint creation also benefits from this.
Clicking a train with the pause tool now toggles the train's paused state.
Incremental research now automatically queues again after being researched.
Added the ability to compare trains in the train designer without having to go to replace mode.
Performance
Optimized vehicle simulation resulting in an overall 10% FPS gain (see CD#52 for details).
Optimized save loading, resulting in 30-50% faster startup.
Optimized ocean simulation resulting in 5-8% FPS gains (in early game).
Optimized performance for placing of large blueprints by up to 90% (depending on the size).
User interface
Added new language: Norwegian
Added train replacement tool with full comparison UI for train replacements.
Added color picker for train line and train colors.
Added vehicle type filters for storage unit.
Improved mods UI, selection screen, and error reporting.
Improved train designer UI and surfaced more useful information.
Trains now notify when loading is interrupted by a fork in the track.
Changed how maintenance is surfaced in entity inspectors, actual resource consumption rate with a progress bar is now shown.
Reshuffled toolbar categories for better usability.
Added WASD / arrow key navigation to the research window and world map.
Holding ALT key keeps floating popups open without requiring interactive mode.
Balancing: Trains
Increased max train speed through medium turns from 60 to 80 km/h.
Reduced air drag by 4x for all trains, affecting the fastest tier 2 trains the most.
Lowered tier 1 steam locomotive fuel consumption from 7.5 to 4.
Removed train top-speed penalty from locomotives pushing wagons, introduced locomotive power penalty instead. This also means that adding a locomotive to any position within a train will never hurt its overall performance.
Increased the cost of locomotives' instant refuel action.
Reduced train build times across the board.
Balancing: Increase capacities
Fuel station I: 40 => 100
Fuel station II: 120 => 200
Fuel station III: 360 => 400
Hydrogen fuel station: 240 => 400
Storage II: 400 => 500
Storage III: 2500 => 3000
Storage IV: 5000 => 6000
Recipes
Added overclocking recipes to seawater pump to allow it to pump 2x more for 3x power.
Increased Liquid dump throughput to match T2 pipe (from 60 to 200 / min).
Mods are no longer loaded on game launch but only after a new or loaded game requests them. This avoids outdated or broken mods affecting the core game.
Introduced mod manifests that provide mod metadata without loading executable files.
Mods can now declare mandatory and optional dependencies, affecting mod load order.
Mods can now be optionally configured in-game based on keys from config.json. Configuration can also be changed when loading an existing game.
Mods can now explicitly process config changes on load based on the loaded vs current mod version.
Mods can now have changelogs that are surfaced in the game.
It is now possible to remove research nodes and unused unlocked prototypes without breaking save compatibility.
New console commands
set_game_speed - to overclock simulation speed beyond 3x speed.
toggle_fog_rendering - to disable fog.
add_markers_to_toolbar - to show source / sink markers outside of sandbox.
Graphics
Improved ocean visuals, including shadows cast onto the water surface.
Removed legacy low-fidelity ocean option.
Locomotives now display unique identification numbers on their models.
Added camera dolly track to Photo Mode for smooth, repeatable camera motion with editable waypoints.
Other
Increased Steam Cloud quota from 2 GB to 4 GB. Note that synced files are all saves, custom maps, and blueprints.
Improved balancing of trucks and excavators, minimizing idle trucks (mining is now up to 17% faster).
Excavators now maintain spacing from each other when mining. The same applies to trucks when dumping.
Loads of smaller bug fixes.
Notable fixes (not an exhaustive list)
Fixed missing side-walls and railings on elevated track intersections.
Fixed incorrect train cars spacing on 45-degree tracks.
Fixed trucks driving off long level crossings and being trapped in between tracks.
Fixed datacenter that was consuming 0.09765% more coolant than defined.
Fixed construction priority resetting on cut/paste.
Fixed trade reputation rising from failed loan payments.
Fixed Unity consumption by mine/lab/oil rig to not consume Unity when not working.
Fixed dump tutorial (slag) not triggering in all cases.
Fixed quick trades costing unity of the next tier.
Fixed quick repair being free instead of disabled (from difficulty settings).
Fixed rocket depots consuming resources while waiting for the transporter.
Fixed nuclear reactor UI not showing reactor as overheated when emergency cooling was active.