Making Games Live Longer With Mods

rmohr02 writes: "Popular Science has an interesting article about people hacking games to get more replay value out of them. It mentions games like Quake and Doom which are still played due to the mods people distribute for them, and that the code for Doom's level editor was made free so hackers could use that code to get what they wanted. It also mentions that the next Team Fortress hack, Team Fortress 2: Brotherhood of Arms, will not be distributed for free."