For my sins, I've become addicted to Euro Truck Simulator II - please, let's move on... to...
Papo Y Yo - it's a brilliant full 3D platform puzzler, brilliant for its style (you're a Brazilian kid running through a city with the power to rearrange the buildings around you in a way occasionally reminiscent of Inception) and its message (it's "about" dealing with a traumatic childhood, in which an alcoholic father is replaced by a huge, lumbering monster obsessed with drinking coconuts and eating giant frogs - symbolising what, exactly, is part of the joy of discovery). I played it to completion in a matter of days - very rare for me - and loved it, I've already started a second play though.
The Long Dark - it's only in Beta but already pretty cool (pardon the joke), a First Person survival sim where the principle enemy is the weather: it's post-apocalyptic, and cold. You start out wearing thin clothes and with not a lot of provisions, in a remote landscape blanketed in snow and populated only with deer, wolves, and maybe a few other small critters - no people, or monsters, which makes a nice change. It's resource-and-time-management on the one hand: activities like cooking, eating, skinning a kill or making tools all eat away at your day, and your calorie count; thirst and hunger need to be watched; and, of course, there's cold - real temperature and wind-chill are factored against your clothes, and dropping temp means calorie burn...
I've survived through my first night (even sleeping costs calories, you know...), repeatedly fumbling around my shelter in actual pitch blackness to avoid wasting matches or precious lamp fuel, breakfasting on a can of old beans at 6am only to go outside to find a storm raging and the temperature down to -26 Celsius, running back inside so as not to freeze to death in minutes rather than hours. It's sandbox mode only at this stage, with two environments in which to survive as long as you can, but the final version will have a story mode as well.