Active as a player during the inter-war years of the Weimar Republic and later as a trainer during the rise of the Third Reich, Schlage is remembered for a game depicted in the science fiction film 2001: A Space Odyssey, which chess writers attributed to him.
During the inter-war period Schlage was active in the lively chess culture of Berlin, where tournaments were commonly held at cafés and restaurants.
"[12] On the other hand, Schlage was ranked as the world's 31st best player in a statistical analysis corresponding to his peak performance (August 1923), which indicated a level of play typical of a grandmaster.
Together with Alexander Alekhine and Efim Bogoljubow, he trained the German national team for the 3rd unofficial Chess Olympiad at Munich 1936.
In August 1939, he trained the best young German players (Klaus Junge (15 years old), Wolfgang Unzicker (14), Edith Keller (17), Karl Krbavic (17), Rudolf Kunath (15), etc.)
[13] In 1910 in Hamburg, Schlage defeated Roesch in a 15-move miniature which opened with the Ruy Lopez; the game was later reproduced in a 1955 collection by Irving Chernev.
[19][20][21][22] Once the black king occupies the critical c7-square and corners its white counterpart, it forces a draw, whether by threefold repetition, stalemate, or agreement.
[25] In 1979, the African country Mali issued a quartet of stamps depicting chess masters; Alekhine, Bogoljubow, and Schlage were represented, together with Dawid Janowski.