Duplo was invented by Walter Joris around Y2K, and published in his amazing book 100 Strategic Game for Pen and Paper.

Duplo in the bookPhoto by me

Like most games in the book Duplo is characterised by pieces being continuously added, never moved or removed. This in combination with the line extension mechanic makes for a fast but rather deep game, difficult to play well!

External links:

• Board Game Geek entry
• World of Abstract Games entry