Slots, like any other casino games, are purely based on luck. The RTP percentage is an indication of what are the chances of winning a game. Titles from leading providers such as Microgaming, NetEnt, Arrow, Azumi, etc., use the RNG (Random Number Generators) to produce mathematically random outcomes and therefore cannot be rigged. Also, the casinos hosting these games should be credible with licenses from credible agencies such as Malta Gaming Authority, Gambling Commission of Great Britain, Government of Gibraltar, etc., to ensure absolute fair play.