A flat 30%, with nothing to soften it
Winnings are the harshest category of income to be taxed on, because none of the usual cushions apply. Under Section 115BB, winnings from lotteries, crossword puzzles, card games, horse races, gambling, betting and television or game shows are taxed at a flat 30%, plus surcharge and cess. Your slab does not apply, so the basic exemption that shelters your first slice of income does not help, you cannot deduct any expense of taking part, and you cannot set off any loss, from these games or from anything else, against the winnings.
Online games sit in their own but identical box. Under Section 115BBJ, the net winnings from an online game are taxed at the same flat 30%, whether the game is one of skill or chance. So a fantasy-sports or gaming-app win is taxed just like a lottery. For a non-resident, the rate and the no-relief rules are exactly the same, there is no gentler treatment for an NRI.
The tax is taken before you are paid
You usually meet this tax as a deduction at source, before the money reaches you. For a lottery or a game-show prize, Section 194B requires the payer to deduct 30% once the winning crosses ₹10,000. For an online game, Section 194BA requires deduction on your net winnings with no threshold at all, applied when you withdraw and on the year-end balance, so every rupee of net winning is covered.
Where a prize is in kind, a car, a holiday, the payer must still ensure the 30% is paid before releasing it, which is why winners are sometimes asked to pay the tax to collect a non-cash prize. Because the deduction is at the full 30% and the tax on the winning is also 30%, there is usually nothing more to pay and nothing to reclaim on the winning itself. But you still report it in your return, and if you have other Indian income the winning does not merge with it, it stays taxed at its own flat rate.