"It's always the same games on sales"
"I wish I had known which game was going to on sales"

If you are one of these guys, you may want to have a look at the that. I noted all sales, gems, promotions made since the beginning (I may have missed some and there may be some mistakes though). You may be able to define some pattern.

You will find which game, on which date, with which % and the number of times it has been on sales so far.

I really hope no one did this before or I am going to cry.

https://rapidshare.com/files/2886075820/GoG_Final.xlsx

This is very helpful, I'm one of those people who needs to know many data (mostly games' prices :p) before purchasing stuff.

Thank you Gilou.