For CoD WaW, from my vantage point, the big issue is that they no longer issue valid cd keys (12 key code that used to be printed on little paper manual with a physical game). If you download the game on steam, you will still have the problem (they don't give you a valid key). So, I recently set up a couple games on different machines (for my kids) by just buying physical copies on ebay (that came with the valid cd keys). They hadn't been used before... I wasn't sure if a used copy/key would work, so I just bought them still in their original plastic wrap. Patched them up to the correct level and they both work great. Hope this helps.