It is necessary to play competitors' games and slots  This is a common truth for ordinary video game designers. While they can be accused of making similar games, they all have to learn how to be players first. But just like video game designers, slot makers, being well-versed in math, still need to understand what players want and what they think. Any good mathematician can make the game reach the intended slot return percentages, and a good slot designer will invest in it "near-misses", the balance of wins and losses and the frequency of features and bonuses to get a big win.