Complex sentence: Avalon Hill became a subsidiary of Monarch Avalon Printing in 1962 (as a way of repaying debts incurred by Roberts), which then ran it for the next 36 years.
Split into simpler sentences: Avalon Hill became a subsidiary of Monarch Avalon Printing in 1962, (as a way of repaying debts incurred by Roberts). Monarch then ran it for the next 36 years.