I suggestion for the holiday shopping season....

Have a sale where we create our own sales' items...

1 game at full price
2 games save 10%
3 games save 20%
4 games save 30%
5 games save 40%
6 or more save 50%

Thanks for considering this idea....

Good for shoppers but not great for GOG. It wouldn't be bad for GOG, necessarily, but it does lessen the chance of making impulse sales. For instance, with the current sliding scale, GOG is probably racking up sales that they would otherwise not get: the customer sees that the entire package price can go down another 10% if she buys just one more game, but none of them are games that she was really looking for... but for an extra couple bucks, why not get it? Customer gets for cheap a game she might not have otherwise purchased and GOG gets a sale that probably would not have occurred.

With the way you mention, it's mostly going to be people clearing out their wishlists and maybe not taking a look at other titles. GOG will end up missing a bunch of those "opportunity sales", and customers might miss out on picking up some hidden gems for cheap.