I think such topic is rare in this forum or gamasutra. I am still learning it, and get some understandings. The calculation is complex, because tons of data have been linked togher. The core of balancing is stable. So which thing should be stable? Fighting cycle time not genius should be stable. For instance, there is a base charactor, and has HP, MP, AD (physical attack), AP (magic attck), MD (physical defence), PD(magic defence), Hit, Miss, Cri. The player has 60 levels and 4 careers, and different crarrer has different skill ( so different cooldown time) fighting cycle time = equivalent HP / equivalent DPS Equivalent HP = charactor HP / ( (1 - damage avoidance rate) * ( 1 - evasion rate) ) You can find many formulars on how to calcualte equivalent DPS. By far the process is not easy. And equipments and skills can change equivalent HP and equivalent DPS greatly. In MMORPG, equipments always play the bigger role on attributes contribution. There are 11 types of equipments, such as helmet, necklace, ring, armor....... Each equipement has 60 levels (or more or less), and each level has five or more colors ( or more, color stands for norma, rare, lengdary...), and each color has 11 qualities ( biigger quality means more enhancement). Some types contribute to HP, and some contribute to AD...so on so on. Spreadsheets have been used for these data heavy calculation. You need to make sure the player's fiighting cycle time maintains stable in different level with different equipments and skills. You have to make more than 50 worksheets to cover above calculations. Finnaly you use VBA to get a simulation. You choose two careers from 4, and set level, then make simulation. The fighting cycle time should be stable. I think it is really hard. I feel difficult on how to organize it. And there a lot of details in the process I don't cover, such as how to set the inital data, and how to define the data of euipqments and skills. Maybe somebody can explain more clearly than me.