What is the ruling on a game in which one buys chicks and birds with real money to produce eggs that are converted into virtual currency and then into real money that is sent to the bank?

The question is not clear enough, but the buying and selling of add-ons in electronic games with real money depends on the ruling of the game itself. If the game is permissible, then the add-ons are benefits that may be bought and sold under the known conditions of sale, such as the sold item being known. Therefore, it is not permissible to purchase unknown add-ons.