Chess is good.
Go is better. To play (or watch games), go to KGS Go Server. To learn about Go, visit Sensei’s Library.
Go is good for everything. For passing time and having fun, for developing logical skills, for developing spatial skills, for music, for science, for fencing, for — lehavdil — Gemara. It may even help with fighting off potential Alzeimer’s.
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In tractate Pesachim, it says that we don’t do an organized Torah study until we are done with bdikas chametz the night of the 14th of Nissan (since we may get so caught up in the study that we forget to do bdikas chametz or do it not thoroughly enough). Think about it: no Torah study the Eve of Pesach. Neither birthday nor yartzeit. (No chess either, though.)