Seconds before civilization as we know it is wiped out by some great cataclysm, a rocket launches and escapes into space. Was it a nuclear war? An asteroid impact? At this point it's unclear. All you know is that you lived through it, and you have a job to do. Deep below the Earth's surface is the Last Sanctuary, an underground bunker protecting a thousand survivors from the devastated, uninhabitable planet above. These people are now your responsibility. Lucky you.

As far as premises for post-apocalyptic video games go, this is pretty damn evocative. The Last Sanctuary, a free browser game created by indie developer Sjoerd Hekking, is entirely text-based, set within the small, glowing monitor of an old IBM computer. But it still manages to paint a vivid picture of this bleak future through its writing, a palpable atmosphere, and an enjoyably retro UI. It's one of the most haunting post-apocalyptic games I've ever played.

Related: This Brilliantly Creepy New Indie Game Is A Strategy Puzzler With A Gruesome Sci-Fi Horror Twist

Your unnamed character now inhabits a space station orbiting Earth, and has been charged with remotely protecting the inhabitants of the Last Sanctuary. "You are burdened with their moral and ethical questions, their administrative needs, and their infrastructure," the game reveals as it explains the nature of your job. "They should be able to survive for 50 years, or until you open the doors." The lives of these people are in your hands, which is a real mindjob.

The Last Sanctuary

Yeah, it's a slightly unbelievable setup. Why would humanity send one person to do this monumentally important job? I guess other rockets could have been destroyed before they managed to take off. It's best not to think about it too much—and you'll stop caring when the residents of the sanctuary start asking you for help. When they need you, you're awoken from stasis (sometimes after years asleep) and have to make tough decisions that can have serious repercussions.

At any time you can pull up a program that monitors the sanctuary. It tells you how many survivors there are, how much medication and food is left, the temperature, how clean the air is, and so on. There's also a bar indicating how much radiation is left on the surface. So it was a nuclear war. You have to constantly monitor the health of the facility—especially when the decisions you're forced to make for the people begin dramatically affecting these readouts.

There's a power surge and you have to quickly divert it, damaging a vital system in the process. But which one? The database that stores all of humanity's remaining knowledge or the comms array? When the survivors pick up a mysterious radio signal coming from the surface, do you answer it? It could be anyone, and advertising that you have a bunker full of food and water might be a bad idea. A battle over territory breaks out. Do you intervene? A lot of people could die.

The Last Sanctuary

Game designer Sid Meier once famously described video games as 'a series of interesting decisions', and even though a lot of people debate the merit of that statement, it's the best way to describe The Last Sanctuary. Wondering what moral or ethical dilemma it's going to throw at you next is incredibly compelling, and I found some choices legitimately hard to make. They're randomised too, so every time you play you'll have a somewhat different experience.

The responsibility is overwhelming. Drifting alone in space, deciding the fate of the last scraps of the human race... it's too much. Worse still, you have to decide when to let these people out—with wildly different outcomes depending on the status of the various gauges on the sanctuary monitor. In one playthrough I wondered what would happen if I opened the doors when the surface was still highly radioactive, and I still regret it. Severe radiation? Bad. Very bad indeed.

The Last Sanctuary is an exceptional piece of interactive fiction. The quality of the writing may be hit and miss, and some of the decisions you're asked to make are a little contrived, but I let these issues slide, because being a space caretaker in this stunningly grim post-apocalyptic future is immensely entertaining. It does a huge amount with very little too. I mean, the entire game is just some green text on a computer floating in space. But it still managed to get under my skin.

Next: The Lion's Song Is The Best Narrative Game You've Never Played