No, this game is not open source. It's developed by the SCS Software s.r.o. and the license is shareware and you can download a demo. To enjoy the full version of the game, you would have to buy it from the supported platforms. If you intend to do that, I recommend Steam platform since the game is delivered digitally and you can access and install it whenever you want from the client after you have logged on with your username and password.