For the case of general demand and cost functions, a game-theoretic problem of the quantity competition analysis in an oligopoly is considered. A cyber-physical system is investigated based on conjectural variations, i.e., assumptions of players about the impact of their actions on the action of the counterparty. A comparative analysis of the conjectural variations for various types of inverse demand function (linear and power) and cost functions (linear, power, quadratic) is carried out. The following main results are obtained. In the linear-quadratic model, the influence of the player’s sales volume increase on the decrease in the environment’s sales volume is less radical than in the linear model. In the power model, a greater absolute value of the environment’s sales volume decrease is observed relative to the linear model. The quadratic-power model is similar in characteristics to the power model with a negative scale effect.