Not least because those ten hours are still throwing up surprises. Everything I feared about the game - that it would become repetitive, and boring, isn't happening. It's a sandbox, but one with a structure of sorts. It lays down breadcrumbs, leading in multiple directions at once, and following the trails is proving irresistible.
Every new location, every alien encounter, every new piece of technology, brings unexpected rewards - another piece of lore, or another mystery, or an unexpected encounter, or a weather system which takes me by surprise. Right now, I'm gradually making my way towards a black hole, which promises a shortcut to the centre of the galaxy... It feels huge, and strange, and empty... and exciting.
But instead of reviewing No Man's Sky right now... I can talk about how it is delivering something I've always looked for in games: a sense of unbound exploration, which has faith in the player's curiosity and imagination.

Years ago, I befriended a bunch of monster-hunting lunatics from the Centre of Fortean Zoology.
I managed to wrangle a book deal off the back of my association with them, after they invited me along on one of the expeditions to discover unknown animals.
Though it had nothing to do with me, the trip had been sponsored by Capcom, in support of Monster Hunter 2.
Ultimately, I ended up having to choose between the book and a TV show - Dani's House - and went with the latter. I still went on the expedition to Guyana, though - and it was among the maddest, most inspiring, few weeks I've ever had. Sadly, we never found the giant anaconda or ape men we'd been searching for... but the experience in and of itself was profound.
Led by an Amerindian chieftain who was descended from an eagle (but was nevertheless a fan of Coldplay and the Ronnie Corbett sitcom Sorry), we trekked across blazing savannah, took an 18-hour, Mad Max-style, bus journey through rainforest and desert, discovered an ancient burial chamber at the top of a mountain - full of clay pots containing human skulls - met a shapeshifting shaman, contemplated fleeing the village we were staying in when it was threatened by a bush fire, got bitten by fish while swimming in the river, and heard bizarre stories about a race of red-faced pygmies... which freaked the living crap out of me.
Our guide shot a cayman with a bow and arrow, which became our dinner, one of our party fell off a mountain and broke her hand, and I struggled with heatstroke, and we ended up having to wash from a bucket one night when we discovered that the lake we'd camped beside was infested with piranha. We trekked to a huge rock sticking out of the ground, and heard the story about the legend of Tebang - who sat atop the rock shaking a necklace of human bones, after infecting the children of the nearby village with a sickness.
On the long walk back to civilisation, we took shelter - exhausted - beneath a rocky outcrop, and watched as vultures circled above our heads, like they do in cartoons.
It remains one of the most punishing and incredible experiences of my life, because even with my companions beside me, I felt so alone. I felt we were treading where others never had, seeing things that were so far beyond my day to day experience. So far from home.
That human instinct for curiosity was being scratched in a way which only video games had ever done before. I could've stayed back in the UK, and not taken the risk, but I couldn't, once that door was opened. That instinct has always been too strong in me. It's too strong in us as a species.
Svante Pääbo, a director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, explains that homo sapient evolutionary impulse to explore like this: "We jump borders. We push into new territory even when we have resources where we are. Other animals don’t do this. Other humans either. Neanderthals were around hundreds of thousands of years, but they never spread around the world.
"In just 50,000 years we covered everything. There’s a kind of madness to it. Sailing out into the ocean, you have no idea what’s on the other side. And now we go to Mars. We never stop. Why?”

Ever since I first played games, I read between the lines. I filled in the gaps, in a quest to see beyond the horizon.
Going right back to Space Invaders, I saw through the simple graphics, and the constraints of the gameplay, and witnessed a planet under attack from alien aggressors.
The intro to the mostly-forgotten Spectrum game Bugaboo (The Flea) was worth more to me than the game itself: it began with a blue planet looming into view, as you approached it in your spacecraft.
I would pretend my TV was the viewport of my rocket... and reload over and over just to get that intro.
Rescue on Fractalus - a game which it's impossible to feel didn't influence No Man's Sky on some level - was denied to me, but I remember watching it being demoed on Tomorrow's World. The procedurally-generated terrain looked so real. I wanted to go to Fractalus so badly. I never got the chance.
I tried so many times to get into Elite - another game to which No Man's Sky owes an undeniable debt - but it felt too abstract, too bogged-down by statistics and maths. I was never invited in, pushed away by a faceload of Excel spreadsheets.
As games got more complex, the environments they offered expanded my imagined horizons even further. For me, Jet Set Willy was never a game about collecting discarded wine glasses. It was about exploring a strange and surreal mansion.
That's what urged me on; to see the next room full of peculiarities... places with names like The Chapel, or The Banyan Tree, or The Forgotten Abbey. It felt like a place with unlimited scope, full of mysteries - and I'd often hear talk of hidden rooms, or secrets placed behind its walls. Who made this place? What is it? What will be behind the next door?
I've always gravitated to games which offered that, which had a sense of place, and allowed you to explore at your own pace. To just wander, as if the developer had opened a portal onto somewhere that had already existed.

Today's sandbox games offer those huge worlds that I always dreamed of, but somehow they're almost too stuffed.
There's so much to do in Grand Theft Auto V, The Witcher III, and the various Assassin's Creeds, that it's impossible not to see the human hand behind the exploration. It's impossible to feel you're stepping foot in a place where nobody has previously trod.
Everything is explained, usually with reams of text, or copious cut scenes. You can't round a corner without another mission being shoved in your face, or an idle NPC demanding your attention. Do this! Look at me! Buy my thing! Play cards! Jump out of a plane! It's like they don't trust the player's attention span. Most modern sandboxes are noisy and loud, and busy, and feel over-designed, like theme park rides.
Somehow, the relative emptiness of the worlds in the likes of Castle Quest on the BBC, or A Link To The Past, or the first Tomb Raider, added to their atmosphere. That sense of isolation, that sense of pioneering. It's something which - thus far - No Man's Sky has nailed, 100%. It's a game which doesn't talk down to the player, and trusts them to make their own entertainment, their own way through the universe. It believes in their ability to fill in the gaps, and revel in the entertainment which comes from exploration in and of itself.
It's something I have very much missed.