It all began more than 20 years ago, in a cramped student flat in Chicago, where two friends, Jason Jones and Alex Seropian, programmed computer games from their living room and hand-assembled the boxes. But next week, Bungie, a company that has grown from a team of two to more than 500 employees, will release the world's most expensive and eagerly awaited video game – to an expected 10 million players.

Many claim that Destiny will revolutionise the face of gaming when it hits shelves globally on 9 September, in the same way that Halo, the influential franchise that put Bungie on the map, did when it was released in 1999. To date, Halo has sold 50m copies.

Destiny will be Bungie's first new project since Halo and its sequels, and the anticipation and secrecy surrounding it has already ensured it is the most pre-ordered piece of entertainment software in history. When a beta demo version was released in July, a record-breaking 4.6 million people played it.

In a sign of the increasingly mainstream nature of video games, Paul McCartney has co-composed the soundtrack – a 50-minute orchestral suite – as well as writing a theme song for the game.

"The hype levels that have surrounded the game have been stratospheric, it's ridiculous," said Alan Ismail, who has racked up more than 15m views on his YouTube gaming video blogs under the name Moreconsole and has worked with Bungie to test out Destiny. "This is definitely a game that is going to change the industry. It's a decade-long project as well, and you see Bungie comparing their game to Star Wars and Lord of the Rings, that kind of epic sci-fi trilogy, and they want to build this universe that will last a decade. It's a pretty insane project if you think about it."

A sci-fi fantasy set in a post-apocalyptic world 700 years in the future, it enables players to become "guardians", travelling through space, either alone or with friends, with the task of investigating and destroying aliens before the human race is wiped out. The project has cost $500m – more than twice the budget of the new Star Wars films.

Derek Carroll, a designer for Bungie who has worked on Destiny for almost five years, said the investment had been strongly focused on the social aspect of the game and of the Destiny universe, which is what has set it apart from other games. It can only be played online, ensuring everyone entering the Destiny universe is connected and can appear and interact in each other's games.

"Destiny is a tremendous undertaking and it is certainly the biggest game I've ever worked on or that possibly anyone's ever worked on," Carroll said. "Destiny is, in our minds, the next big step of pervasive social connections and really subtle social connections that you don't have to opt into, they are just always there. The world of Destiny is filled with other players."

He added: "I would say Bungie aspires for Destiny to be a hobby, for you to spend your time playing it. There is a story that we are developing and everyone will experience the bones of it, but they will experience it in their own way, depending on if they are with friends or of they run into strangers. The people and the social interactions are what take it to the next level. My personal story going through the game will always be different from the next player, and we want people to want to be in the world, and really immerse themselves in it."

The Bungie team, he added, had spent years "throwing away bad ideas and even good ideas that weren't ambitious enough or exciting enough" to get to this point. This week, the Bungie studio unveiled a Destiny Planet View website, which, using Google Street View technology, lets players peruse the spectacular game environments on Mars, Venus and the Moon as they would any real-world landscape.

Carroll said: "The art team spent years nailing the tone and figuring out what Destiny would look like and how to create this beautiful world that is worthy of heroes and that you want to inhabit, want to be there. We're very proud that anywhere you walk in Destiny you can find a beautiful sunset or an interesting piece of humanity's past that captures your eye and invites you to learn."

Ismail, who has played the game, also praised the social element of Destiny, which he said was unlike any other game on the market and had been generating buzz for over a year, as the notoriously secretive Bungie drip-fed tantalising titbits to the gaming community.

He said: "It is interesting, because when playing Destiny you bump into random players and that has never really happened in a first-person shooter before. So you could be blasting aliens in the face, and you see another guardian on the horizon walking towards you and you can interact with them using the game's gestures, so that's pretty exciting."

He added: "I think that's the reason it's going to be marked apart from other first-person shooters, the fact that there are going to be these social, public spaces where you can collide with other real-time players in this vast open world. Also the depth to which you can customise your character and make something that is unique to you is something you don't usually get in a first-person shooter game. So, as a long-term video game fan in general it's an amazing experience."Bungie has estimated that 10 million people will hit the game's servers when it launches on 9 September for Xbox 360, Xbox One, PS3 and PS4, with Carroll jokingly adding that the company's goal with Destiny was to "break the internet".

Matthew Pellett, editor of the Official PlayStation magazine, said he had already spent almost 50 hours playing the beta version of the game and expected that the hype around it would only increase on its release.

"If you look at Destiny's features in isolation, actually it isn't really doing anything that hasn't been done in other games before," said Pellett. "The online features, the social features, the shooting mechanics, the loot – they appear scattered across other games. But Destiny is the first title to bring them together into one cohesive package, and that is what people are excited about."

He added: "When the final game comes out, I'm predicting it is going to be massive and I am sure it is going to introduce a new way of looking at these mechanics. In a couple of years, I think a lot more people will be doing what Bungie is doing with Destiny."