This is true of most shopping. It's designed that way. Milk and bread are never at the front of the supermarket. They are way in the back. So you have to walk through the entire store and see everything on sale on the way to the milk.
I never went into Nieman Marcus or Nordstrom, bought one thing, and left. They position the blouses or jeans next to each other with one or the other always on sale. All the golden goose shoes are next to the jeans and they always have a special discount. Places like Target and Costco are designed around getting you to buy a bunch of stuff on the way- BOGO, Digital Coupons, discounts that only kick in when you buy #X of product or Match 3 specials.
Ever been to RH? They nickel and dime you for buying an accent chair.
The method digital games use is novel, but the practice and expense of "psychological" tricks for sales are long practiced.