There are a number of interesting aspects to the simulated nature of the Freeway Network and ecosystem which have not necessarily been possible or done before, and so may have a number of interesting side effects from a taxation point of view.
It would be up to each individual to figure out how gains in a gamified simulation of network-enhanced trading would be taxed. Would they be taxed every time you played the game, or would they be taxed when you managed to exchange simulated value gains for property? We are certainly not tax advisors, so everyone has to figure these things out for themselves.