Slot Machines RTP Optimization with Genetic Algorithms Todor Balabanov1 1 , Iliyan Zankinski 1 and Bozhidar Shumanov 1 Institute of Information and Communication Technologies, Bulgarian Academy of Science, acad. G. Bonchev St., Block 2, 1113 Sofia, Bulgaria, todorb@iinf.bas.bg, http://www.iict.bas.bg/ Abstract. Slot machine RTP optimization problem is usually solved by hand adjustment of the symbols placed on the game reels. By controlling symbols distribution it is possible to achieve desired return to player percent (RTP), but also some other parameters can be adjusted (for example free spins frequency or bonus game frequency). In this paper, RTP optimization automation is proposed based on genetic algorithms. Keywords: slot machines, RTP, genetic algorithms, optimization 1 Introduction Slot machines are electronic gambling devices that offer variety of games. They are found mainly at casinos and some bars. Slot machines are relatively inexpen- sive to run compared to roulette, blackjack or poker, that is why they become very popular and very profitable form of gambling. The game consists of three or five reels which spin when button is pushed. The game pays off according patterns of symbols visualized on the screen after spin stop. The main scope in this paper is about symbols distribution on the machine reels.On each reel there are ordered symbols (usually represented with numbers in math models). The order in which symbols are presented on the reel is discrete probability distribu- tion. According symbols distribution, different wining combinations can appear on the game screen. Mathematicians who develop slot machine reels have the task to select such discrete probability distribution which will produce certain RTP. The value of RTP (return to player) is calculated by division of money won over money lost multiplied by one hundred. The RTP value is very important for slot machine vendors, because this is the main gambling game parameter which is under government regulation. The RTP value has mathematical meaning as expected value. The other interesting parameter of the slot machine games is volatility, but this parameter is not discussed in this study, because it is less of- ten taken into account during government regulations. The proposed approach for symbols discrete distribution optimization can be very handy for mathemati- cians who are working on new slot gambling games.