Ive just been in to continue my 70h+ cont game. I was playing a multiplayer lastnight for about 8 hours and over that time manually saved about 8 times.
Oct 11, 2014 - Backing up game saves from Steam has never even crossed my mind. Like for example if I want to play anno 2070 and use steam to launch it. Kodi irdeto 2 klyuchi.
Now in my saved games there are only 6 saves.and it's as iff my cont game has been pushed to the end and then been deleted as if it can only save 6 games at the most. I noticed this whilst only playing my cont game weeks ago but because it was only my 1 game being played it didnt bother me. 
I have checked all the filters and only 6 still, aswell as chacked the save folder under my docs and there are only 6. ANY advice would be much appreciated. Ya, what Melkathi said. I had the same thing happen to an 80+ hour continuous game.
I didn't save it indidually. I lost it when I did another type of game. I wasn't happy but moved on and now have a contiuous I like better. With it's own named save.
Backing them up will help sure, but you don't need to (I was gonna make a script to do it). But you just need to create a save file. Pretty simple, and it's certainly not the only game that overwrites autosaves/quick saves.
Games have been doing that for decades. I should have known better, which is why I didn't freak.