Question: what is the biggest selling game of all time
[{'answer': 'Tetris', 'provenance': [{'wikipedia_id': '1617333', 'title': 'List of best-selling video games', 'start_paragraph_id': 1, 'start_character': 294, 'end_paragraph_id': 1, 'end_character': 300, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]