Since the original is no longer on major storefronts, most players have moved to its official successors, which improved upon these deep features:

If you specifically want a free game, the Epic Games Store occasionally gives away titles in this genre (like MudRunner in the past), so it's worth checking their weekly rotations.

Searching for a "free full game download" of can be tricky because the original game was officially removed from Steam in early 2021 due to licensing and publisher disputes. While some third-party sites like Softonic may list "free" versions, these are often limited demos or older, unofficial builds.