The game is browser based and it is also a mobile game. If you're having trouble reaching the browser version please file a support ticket with a screenshot of where you are redirected and we will get back to you as soon as we can.
The browser version can be found at http://www.rail-nation.com/home/
Use the play button to sign up through a social media form, which allows you to get your quest started. then use the above link to access the game fully.
Also, with the mobile version, not only does loading your game with the mobile version allow you an extra 200 gold, you can level yourself up through the mobile game, and then log in on the browser game, to get your screenshots for your quests.