since rummy as a game played online, you can file a cheating case under IPC and under section 66 of information technology act against online rummy games and recover your money.
Section 66 in The Information Technology Act, 2000
71 ,66 Computer related offences. -If any person, dishonestly or fraudulently, does any act referred to in section 43, he shall be punishable with imprisonment for a term which may extend to three years or with fine which may extend to five lakh rupees or with both. Explanation. -For the purposes of this section,-
(a) the word “dishonestly” shall have the meaning assigned to it in section 24 of the Indian Penal Code (45 of 1860),
(b) the word “fraudulently” shall have the meaning assigned to it in section 25 of the Indian Penal Code (45 of 1860).
Section 66 of the IT Act defines the punishment for messages through a computer or any other communication device like a mobile phone or a tablet. A conviction can fetch a maximum of three years in jail and a fine.
Globally India having the second largest online population, Online Games have become big business in India. Gambling has become one of the most popular and lucrative businesses
on Internet. Online Games are attracting 75 % of youth, majorly male. Online Games in India amounted to lakhs of crores revenue in 2016 and future looks beyond imaginary.
Indian software and mobile revolution has drawn plenty of attention in the last couple of years due to cheaper cost of console devices, high technology and well developed infrastructure of e-payments resulted in Online Game Industry witnessing massive evolution silently. Internet provided platform to bet or gamble without cognisance of parents and family members and get addicted to various Online Games such as Lottery, Racing, betting, Casino, Rummy, Poker Etc. Annual game tournaments are organised around the world and sponsors offer great prizes. According to recent survey, three Indian companies Teen Patti, Ultimate Teen Patti, Teen Patti Gold occupied top 4, 6 and 8th ranks in the world.
Reference: section 66 IT act 2000
section 24 ipc
section 25 ipc