Is it okay to play chess or to study for a test on Shabbat and holidays? Under what circumstances is this permitted?

Shabbat is for better things than playing chess or studying for tests. Nonetheless it is not prohibited to play chess – especially if the alternative is worse. (Shmirat Shabbat Cehilchata, 16, 34) It is prohibited to use Shabbat to prepare for the week day; therefore studying for a test on Shabbat is wrong. (ibid 29, 47) As same as for chess – not prohibited but not recommended. (ibid)