Games aren't really "lost" because their source code is lost, as long as copies of the game continue to exist out there somewhere.
Which don't last forever. I have media from 2002-2003 that already has bit rot.
I am actually researching gaming prototypes in my spare time, leading up to an eventual PhD. Games disappear more often than we would like. Gaming archives aren't kept. Places go out of business. Here is a quick write up I did on reddit :
This :
http://ptoponline.com/?p=945
Is the most basic of it really.
I plan on doing a more complete write-up at some point. But basically, hundreds of prototypes are created every year, most of them are disposed of and never thought of again. But just like deleted scenes in movies, or lost TV shows of popular series (think Doctor Who), the history of games are important. Games aren't just a passing fad.
Right now, preservation is mostly focused on the end point, in preserving the games that came out. But the others are just as important, you can learn a lot from a prototype. There can be good ideas within one, or there could be a thousand bad ideas. Imagine if a game programmer had a chance to sit down and look at it and see why?
Ask companies like SEGA how it feels to lose source code. There is a monetary benefit to preserving the data. Being able to jump back 20 or 30 years in a companies history, and to pull out individual assets, has the potential to make money. But if that data is being thrown out (literally), then there is nothing to be gained.
So what I try to do right now is raise awareness to developers and the gaming community as a whole that these things matter. If we don't back them up now, there simply won't be anything to save later. Bit rot is only going to claim more and more data as time goes on. Data backups are nearing the end of their shelf lives, assuming that they were stored properly in the first place.
How can we access the things that are backed up, what kind of hardware is required to get there? And software? What about licenses to compile the software? And even once you have the game, how are you going to play it? Modifying a system, which could be illegal? Emulators? But what about a PS3 game, for instance?
Ultimately, the companies need to have some sort of reliable, uniform system to ensure they have the data. Beyond that, an external system needs to be designed. What happens when a company goes out of business? If the sole holder of the data dies? Morbid, but it could happen.
I just know I would rather have the data safely backed up now, than to have to pick up the pieces and dig through garbage to find remnants of what was and what could have been.
And of course, there needs to be a way to play the games. Games are pointless without the interactive element.