Online games are one possibility that has been discussed. Beyond the initial reaction that reviewing old transaction data is rarely seen as fun—unless Tesco thinks its shoppers are alarmingly easily amused—the game element could prove to be a serious mistake.
Let's not get into what the games could possibly be. (Hey, boys and girls! Can you spot the 10 worst times we overcharged you? How many rip-offs can you find in one minute? Wives, how many of your husbands' purchases of flowers and candy did you never see? Can you unlock our access code and find where he sent them?)
Instead, let's consider whether games are the best way to offer access to this information. Marketing Magazine quoted a former Capital One marketing director, Justin Basini, as discussing the explosive nature of this data: "What has stopped a lot of companies is the concern that people will get freaked out by how much data is held on them. Due to the sheer volume of data involved in Clubcard, if Tesco mucks about with it or takes a misstep, this could prove risky."
Basini's points—and concerns—are the correct ones. Given the intense emotions at play, an attempt to treat this rule lightheartedly could backfire in so many ways.
On the other hand, dealt with seriously and with good integrated analytics, much good could happen. Consider a program that analyzes how long it takes a particular family to go through soap, bread or coffee and then alerts them when the program anticipates they are about to run out. Or one that flags wasteful purchases. Or a package where shoppers could enter in any dietary (low-salt, low-carbs, no nuts, no gluten, etc.) or health/lifestyle (no latex, nothing not-baby-friendly) concerns and have it flag any purchases that violate their preferences. Even a budget program that helps a shopper keep to a requested limit.
Giving shoppers access to their purchase histories can be helpful to shoppers and to retailers. But make fun of it at your own potential-peanut-allergy peril.