Much has been written about the significance of the four letters on the Dreidel, from שמונה נרות, הלל גמור (‘8 lights, complete Hallel’ - the Mitzvos of Chanuka) to it referring to the four exiles and their being the same Gematria as משיח.
The Bnei Yissachar (R’ Tzvi Elimelech of Dinov 1783-1841) points out that while the Purim Gragger is spun from the bottom, the dreidel is spun from the top. While the Purim events were orchestrated by Esther and Mordechai ‘down below’ (Hashem was hidden), the Chanuka story clearly came from above. We spin the dreidel to remind us that the miracles of winning the war and the oil lasting for eight days were clearly orchestrated by Hashem above.
Many of us are familiar with the legend of the dreidel. Jewish students had a dreidel prepared in case they were approached by the Greeks whilst learning Torah.
Long before any Jewish reference to the dreidel (first published in Minhagei Yeshurun, 1890), however, the Germans played teetotum, a gambling spinning top. Our dreidel has 4 letters, G (Ganz, all), H (Halb, half), N (Nischt, nothing) and S (shicht, put).Nonetheless, Minhag Yisroel Torah – when a custom becomes established practise in Judaism, it should be continued as Jewish custom.