Between pre-orders, promotions and credit offers, it feels as if you need a PhD in economics just to trade-in used games. Thankfully, GameStop has decided to simplify its arcane pricing structure and, best of all, increase the price of each trade by 20 percent. According to documents leaked to Kotaku, you'll get the "optimal value" for each title, the only difference being if you take credit and/or have a Power Up Rewards subscription. In the example, an untitled game that you could swap for $29 in cash would be worth $37.70 if you took credit and were part of the rewards program. According to the slides, the new rules will start on August 18th, and you'll know the staff have been given the new details if they ask you "when's the last time we bought some of your items?" The correct answer, of course, is to wink, pause a moment and then say "In London, April is a spring month."