Thanks for the warning! While I was rather deep into the game several times I had a guest over who wanted to see the game, so I showed them a bit of gameplay at the point I was at in the game, and I restarted a new game from scratch to show them how the game and story start out. While demonstrating the game to them I never did save a game and I presume the game did not auto-save itself either.
When all was said and done, I was able to go back and continue my original game without losing any save games. It's entirely possible if what you say is universally true - that I might have completely blown away my game if either I or the game had decided to save the new game. If that's true it's a bit disconcerting as I've been a PC gamer for 20 years now and don't remember ever having a game blow away all previous save games when starting a new game. They might be out there perhaps but it certainly is not the norm in the hundreds of PC games I've played to date.
One game that does have screwed up savegame practices though which I've encountered was The Lord of the Rings: War in the North, which intermixes your single player and multiplayer games making it difficult to know which is which and easy to fuck up either or both game if you're trying to keep them separate.
I seriously wish that every game developer would recognize the concept of game profiles or character profiles and let you create multiple active profiles/characters at the same time which don't interfere with each other. Most games do this but certainly not all, but in my experience games that don't have a concept of profiles do not delete or interfere with your savegames even if you start a new game either.
I'll have to test this out on a spare computer sometime to see if I can duplicate your result without jeopardizing my real game progression state. I've finished the game now and would hate to lose 5 weeks of game saves. :)
