The most important thing that you need to understand about slots game is there is a math that is running behind it. The math is designed to distribute the winnings over various symbols on the slot reels based on completely random outcome.
What you need to ensure is whether the RTP or Return to Player mentioned on the paytable. This gives a theoretical casino edge over a million or 10 million spins. Typically around 95%, it means for every 10 lakh amount invested, casino only keeps Rs. 50,000 and other 9,50,000 is distributed to players.