In response to post #24990149. The availability of mods for a game extend the shelf-life of a game and mods contributed to the fact that Skyrim was still $59.99 for two years after release. I myself, bought Skyrim for $59.99 a year after it was released after seeing YouTube videos of all the mods that made the game look fantastic and all of the changes that corrected deficiencies in play (from my perspective) and added new functionality that improved on the base game. Also consider that the SDK allowed for unofficial patches that squashed all sorts of bugs in the game. That also extends shelf-life by allowing the community to correct issues that might have killed the desire of others to buy a "buggy game". (Assassin's Creed anyone?) The cherry on top is that Bethesda didn't have to foot the bill for developers to fix these bugs. I see SDKs as a big win for companies with the gumption to release them.