This is possibly premature, but I'm worried that Prey might have fallen through the cracks. I don't hear it talked about that much now. Don't wait for a sale. Don't dismiss it because it looks a little sterile in screenshots. Prey is exactly the game that long-time RPS readers have been praying for, for decades. (Pun possibly intended).
As much as I accept and like them in their own right, BioShock wasn't System Shock and Dishonored wasn't Thief. Prey is the closest we've had to that revered immersive sim/System Shock model since the glory days. It's got this alien invasion plot and no shortage of shooting, plus a sideline in magical powers that can be left alone entirely if you prefer (I did), but what it really is is a game about exploring one big place. Learning it, conquering it, loving it.
A game about opening doors, and finding out how everything connects, slowly turning your world from a series of unfamilair areas into one inter-connected space that you know the layout of intimately. Inhabiting a place for dozens of hours, not moving progressively through several of them.
Hacking security stations, sneaking through maintenance tunnels, fixing lifts and, once in a while, exiting the space station for low-gravity wander around its vast exterior. Hours and hours and hours of bending this place to your own will. I haven't enjoyed another game more all year.