Steam is the most common hub for PC sims like Train Sim World .
If you are looking for a community-driven, open-source project, Open Rails is a fantastic choice. It is compatible with older Microsoft Train Simulator (MSTS) content but features its own modern engine. It is completely free to download and use.
Are you more interested in the locomotives, or do you prefer a relaxing journey where you can enjoy the scenery? Train Travel Simulator Free Download
It sounds like you're looking for a way to dive into the world of train simulation without breaking the bank. Whether you want to master complex controls or just enjoy a scenic ride, there are several high-quality "free-to-start" and entirely free options available. Top "Free-to-Start" & Free Simulators
Many premium simulators offer free "demo" or "starter" versions that act as a gateway. Steam is the most common hub for PC
For a more casual experience that is very popular on mobile, you can play Indian Train Simulator for free. While built for mobile, you can run it on a PC using an emulator like BlueStacks . How to Get Started
Train Simulator 2019 Tutorial: Manual Reskin and Scenario Installation It is completely free to download and use
Sites like UKTrainSim often host "freeware packs" that add new routes and trains to existing games at no extra cost.