Online PC retailer and CD Projekt affiliate GOG is giving away classic Interplay RPG Fallout for the next 48 hours.

As announced at CD Projekt's Spring Conference earlier today, it's a way of saying thank you to existing customers and a welcome to those checking out the recently revamped site for the first time.

The store also re-stated that it will start offering newer titles in addition to its library of classic games. Indies like Botanicula, from Machinarium developer Amanita Design, will be a focus but there'll be more mainstream fare too, including a premium DRM-free version of the first game in the Assassin's Creed series.

An early story concept for the first game in the hugely popular Fallout series saw you zipping back and forth in time, traveling through space and battling sentient dinosaurs, creator Tim Cain has revealed.

Speaking at a post-mortem panel at GDC in San Francisco today, Cain explained that the game's story morphed a number of times before its eventual post-apocalyptic setting was settled upon.

At first, it was going to be a traditional Dungeons & Dragons fantasy game.

"A lot of people who came on board said we could do something that's better than D&D - let's put our own twist on that," he recalled.

"We quickly threw that out as there were so many other fantasy games being developed. This is the one choice we made that saved us from being canceled."

Then came something rather more ambitious.

"Our second idea was epic. You started in the modern world, you were thrown back in time, you killed the monkey that would evolve into modern humans, you went through space, you went to the future which was ruled by dinosaurs, you were then exiled to a fantasy planet where magic took you back through the timeline, and then you came back to the modern world to save your girlfriend.

"It's weird even hearing myself talking about it now, but we were really going to go with this. One of the other producers kind of slapped me and said 'there's no way you're ever going to get this story made. You can work on it for years and nobody is ever going to do it'.

Sure enough, Cain and his team scrapped the idea. However, they held on to the extra-terrestrial theme for their next pass. That concept saw aliens invade earth and conquer all but one its cities. The game's hero would then venture out of this safe zone to fight back.

"This is what morphed into Fallout - the idea of a vault that you left and went out into the wasteland," said Cain.

However, getting the game finished and onto shelves proved a very challenging process, with the title nearly axed on a number of separate occasions.

Its first brush with cancellation arose when publisher Interplay picked up the Forgotten Realms and Planescape D&D licenses. Some at the company thought that a new RPG IP might detract from sales of those titles. However, Cain "begged" boss Brian Fargo not to pull the plug and Interplay duly let it live.

It had another close call when Steve Jackson's GURP role playing brand, which Fallout was initially tied into, decided the game was too violent and didn't approve of the art style.

"It was too late to change anything," explained Cain. "I figured we were going to be canceled."

But management gave Cain a last minute reprieve.

"I was asked to write a new combat system. We had a week to design it and a week to code it. If we could do that we wouldn't be canceled. I'm not exactly sure how we did it. I know we drank a lot of soda, we were there all the time, I know we smelled bad too, but we did it."

There was one more shaky moment just before launch. European ratings boards refused to classify the game for release as it allowed the player to kill children.

"We allowed it. We just said it's in the game. If you shoot them it's a huge penalty to karma. You're really disliked, there are places that won't sell to you, there are people that will shoot you on sight. We thought people can decide what they want to do.

"But Europe said no. They wouldn't even sell the game. We didn't have time to redo the quests so we just deleted kids off the disc [for the European release]. The story references children but you never actually see any."

Cain also discussed the struggles the team had coming up with a name for the game. It was originally going to be titled Vault13 but Interplay's marketing team rejected it as it "didn't give any sense of what the game was about."

"They suggested things like Aftermath, Survivor and the wonderfully generic Post Nuclear Adventure," recalled Cain.

"What eventually happened was Brian Fargo took the game home and played it over the weekend. He came back and put the CD on my desk and said 'you should call it Fallout'. It was a brilliant name - it really captured the essence of the game."

And the rest is history. The game launched on PC in 1997 to huge critical and commercial success and a franchise was born.

Cain now works as a senior programmer at Obsidian - the developer behind last year's Fallout: New Vegas.