The most popular slots that pay real money are generally those with a high RTP, such as Ugga Bugga (99.07%), Mega Joker (99%), and 1429 Uncharted Seas (98.60%). RTP ensures that players stand a reasonable chance of winning at online games slots. So, for example, if a slot title has an RTP of 99%, then for each $100 wagered by the player, $99 should go back in their pocket over a period of time.