Answer
(Fatwa: 188/131/D=1433)
It is unlawful and squandering to play crackers. Also it is unlawful to sell it and make it. It has no lawful use but extravagance and wastage of time and money. The holy Quran says that squanderers are the brother of Satans.
إِنَّ الْمُبَذِّرِينَ كَانُواْ إِخْوَانَ الشَّيَاطِينِ [الإسراء : 27]
Hence you should give up this business and choose any other lawful source of income. In-sha-Allah, they shall have blessings and safety from curse.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband