Next week, you'll be able to take your old games to Walmart and trade them in. You'll get credit for them—good for buying socks, giant liters of soda or cat food—but you won't be getting cash.

Trade-ins and the resale market are a great benefit to cost-conscious gamers (not to mention retailers gigging the trade-in values and resale markups). They're also a pain in the ass for developers, especially the smaller ones, who face creating popular but poor-selling titles because everyone swaps it around. In an…