Bepuzzled

123456
Across
  1. 2. One of the top-selling video games of all time and the first game to make it into space
  2. 5. The Sphinx’s riddle-“What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?”
  3. 6. He is a retired Belgian police officer turned world famous private detective with a peculiar moustache
Down
  1. 1. Three times as long as it is wide, and one fifth as thick as its length (hint: game)
  2. 3. The world's oldest riddle-“There is a house. One enters it blind and comes out seeing. What is it?”
  3. 4. Mathematician vital to allies winning WW2