Why did early artificial intelligence systems often focus on board games like checkers and chess?

The correct answer highlights that early artificial intelligence systems focused on board games like checkers and chess because these games have set rules and patterns that make it easier for AI to simulate intelligent behavior. The structured nature of these games allows algorithms to process the vast number of possible moves and outcomes, employing methods like minimax algorithms and heuristics. These methodologies make it feasible to evaluate numerous game states and develop strategies that can compete against human players.

In contrast, while the popularity of these games may attract interest from developers, it is the defined rules and predictable patterns that truly enable the development of AI capabilities. Additionally, complex emotional understanding, which is not a requirement in games like chess or checkers, poses challenges that were not a focus in early AI research. The number of players involved is irrelevant in the context of why these games were selected; the emphasis was on the complexity and structured gameplay that facilitated the AI's capability to demonstrate intelligence.