The board game market was valued at $7.2 billion in 2017 and is projected to reach $12 billion by 2023. Over 1400 board games were published in 2019. There are two main schools of board game design - European games focus on simple but attractive components, strategy, and short play times, while American games emphasize theme, detailed components, randomness, and longer play times. Popular board game mechanics include worker placement, tile placement, deck building, and area control. Games can also be classified by complexity from gateway to heavy games, and by level of cooperation from fully competitive to fully cooperative.