If you bought the game through the humble store or any of the other game stores (except iOS), go back to your purchases page of that game store as the developer has provided steam keys for every purchase.
More info is available in a dedicated thread in the community hub on steam.
Hey guys, for some reason, in running a search for Train Simulator 2013, the correct page never shows up, only a stub page that @jeff created. I started editing the stub, thinking the page was lost in the site conversion. Somehow, I found the correct page.
Get Most Wanted since your friends are still playing the game and you can start some rivalries.
The multiplayer is great and will keep you entertained. Working through your way up the most wanted list/single player mode will take you a few hours.
Let some time pass and pick up far cry 3 in February when you should see some retail price reductions. At the lower price points you might be able to convince that same group of friends to join in jumping into FC3.