Personally, I'm really excited about what's going to happen to Elite Dangerous in 2018.
Elite is an open world RPG space sim set in 3304, and it's quite a huge game. While, shure, the game has been out for a very long time, the game is constantly changing and fleshing out itself with new things to do, and expansions on the story/lore sides of the game. Especially recently, with the return of the Thargoids, (a hostile alien race seen in the earlier 1983 game) and all sorts of other stuff like the Formidine rift conspiracy.
I'm really looking forward to what's going to happen in the game in 2018!