Quick answer
Transport Fever 3 has 41 achievements: 4 for the campaign and 37 for free game.[1][2] The official manual warns that achievements "are generally unavailable if non-cosmetic mods are used or the gameplay settings are deviating from standard values". If you are hunting achievements, play with standard settings and cosmetic-only mods.[2]
The conditions below are quoted from Steam's global achievements page. Grouping follows the official manual.[1][2]
Campaign (4)
| Achievement | How to unlock |
|---|---|
| The Journey Begins | Complete the first campaign mission. |
| Story Master | Complete all missions of the campaign. |
| Story Legend | Collect every star in every mission of the campaign. |
| Phalerist | Earn all medals of the entire campaign. |
For mission goals, stars and medals, see the campaign guide.
Free Game: first time (11)
| Achievement | How to unlock |
|---|---|
| All Aboard | First passenger gets on board of a passenger vehicle in Free Game. |
| Package Arrived | First cargo item is delivered to a destination in Free Game. |
| On Behalf Of | Finish the first subsidy contract successfully in Free Game. |
| Caretaker | Satisfy a town's supply rating in Free Game. |
| Urban Development | Let the first town expand to a higher level in Free Game. |
| Increased Demand | Cause a town to have demand for an additional cargo type in Free Game. |
| Promotion | Gain a company rank for the first time in Free Game. |
| Offshore | First helicopter landing on an oil platform in Free Game. |
| Landscaper | Plant a tree in Free Game. |
| Timekeeper | Change the daytime in Free Game. |
| Weatherman | Change the weather in Free Game. |
Free Game: within one map (12)
| Achievement | How to unlock |
|---|---|
| Megatropolis | Have a town with a population of at least 3,000 in Free Game. |
| Populated Country | Have a population of 50,000 on your map in Free Game. |
| Warehousing Titan | Store over 10,000 cargo items in a single warehouse in Free Game. |
| Bicentennial Tycoon | Have played a Free Game from 1900 until 2000. |
| Subsidy Streak | Have successfully completed 10 subsidies in a row in Free Game. |
| Carreer Ladder | Reach the highest company title in Free Game. |
| Summit Stopover | Have a train stopping at a station situated over 500 meters in Free Game. |
| Bank's Best Friend | Have paid over 10 million in interest to the bank in Free Game. |
| Heritage Fleet | Have all available ship types from 1900 to 2050 in operation in Free Game. |
| Boost the Pack | Have the boosters active for 10 industries at the same time in Free Game. |
| Car Imperium | Have an industry produce 500 cars within 12 months in Free Game. |
| Centralized | Build all 10 landmarks in one municipal area in Free Game. |
Steam spells it "Carreer Ladder"; the manual writes "Career Ladder". For Car Imperium, Steam says "500 cars" while the manual says "500 vehicles".[1][2]
Free Game: across all your maps (10)
| Achievement | How to unlock |
|---|---|
| Globetrotter | Play a Free Game in all climate zones. |
| Tycoon of Tycoons | Earn the company title Tycoon in every climate zone in Free Game (combined). |
| Master Salesman | Deliver every cargo type available in any climate zone in Free Game (combined). |
| Around the World | Build a total of 40,075 km of streets and tracks in Free Game (combined). |
| Passenger Pioneer | Transport a total of 1,000,000 passengers in Free Game (combined). |
| Cargo Pioneer | Transport a total of 1,000,000 cargo items in Free Game (combined). |
| Global Population | Increase the total population of all your Free Games by 100.000 (combined). |
| Connoisseur | Use every vehicle at least once in Free Game (combined). |
| Evil Money | Earn a cumulative one hundred billion dollar in Free Game (combined). |
| Animal Lover | Spot every animal in the game at least once while playing Free Game (combined). |
Fun (4)
| Achievement | How to unlock |
|---|---|
| Encounter of the 3rd Kind | Catch an UFO for the first time in Free Game. (Steam hides this condition; the text is from the official manual.)[2] |
| Oldschool | Use a steam locomotive in the 2000s in Free Game. |
| It Wasn't Me | Get a town reputation rating of 0% in Free Game. |
| Perfectionist | Demolish and rebuild a station twice in a row in Free Game. |
Easy early unlocks
Several achievements come from simple actions in your first free game: changing the time of day (Timekeeper), changing the weather (Weatherman), planting a tree (Landscaper), and demolishing and rebuilding a station twice in a row (Perfectionist).[1]
Open question: Connoisseur ("use every vehicle") and Animal Lover ("spot every animal") may involve vehicles or animals that come only with the Deluxe Edition or the pre-order pack (editions). Neither Steam nor the manual says whether those are required.