A method for presenting wagering games on a wagering game machine is described herein. The method can include detecting, by an add-on gaming system of the wagering game machine, a message indicating occurrence of a first wagering game on the wager game machine. The method can further include initiating, by the add-on gaming system, a second wagering game in parallel with the first wagering game on a display device native to the wagering game machine, where the presenting is in response to the detecting the message.