It is permissible.
It is prohibited to play any game that is based on competition and was invented to gain money like playing cards or chess even if such playing was without betting.
The mentioned sermon is famous and was narrated by different chains of narrators. Furthermore, if the one who narrates an incident or a narration that does not support some of his beliefs and even goes against him, then this is an indication that the narration is true. It is known that some of the content of this sermon does not correspond to the beliefs of the enemies of the Ahlulbait (peace be upon them); therefore, the authenticity of the sermon is beyond doubt.
Mysticism is a new term that was introduced after the time of the infallible Imams (peace be upon them) and it is not part of their teachings. A believer can strengthen his relationship with Almighty Allah and seek closeness to Him by referring to the Holy Book and the narrations of the Ahlulbait (peace be upon them) as much as possible. When Almighty Allah sees the sincerity and good intention in His slave He would bless Him with bounties.