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The game , as well as the three follow on gamettes , was notable for its open-endedness , a trend in tactical board wargaming beginning from the late 1960s , and at least as early as far as Avalon Hill was concerned with PanzerBlitz .
 Avalon Hill
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Avalon Hill