The document discusses game loops, which are the core repetitive actions players perform in social games. It provides examples of good and bad game loops, and emphasizes that good loops should be fun to repeat, have few steps, and provide closure and rewards. The document also discusses adding "smart depth" by including extra strategic layers on top of the core loop. It notes game loops should be tested and verified. The last part discusses an example city-building game loop involving placing houses, collecting income, and un-fogging maps.