Put your knowledge of 20th century history to the test. To complete each timeline puzzle, the player must position the various historical events into correct chronological order. A variety of straightforward entries have been chosen from multiple categories such as, US and world history, wars, politics, entertainment and the arts. This app has nine levels of difficulty to choose from. The complexity is based on the player’s selection of play mode and time span. Play mode levels are low, moderate, or difficult and time span choices are one, two, or three decades. Hours of fun for the novice or history buff.