Progress towards the broader vision of computationally exploring fitness landscapes and mapping genotypes to phenotypes requires the ability to simulate how gene regulation in complex networks affects the dynamics of time series of regulated molecules. After a brief overview of how this problem fits into the broader context of a mechanistic framework for evolutionary systems biology, I will use a simple example gene regulatory network for illustrating how the Evolvix modeling language can help to obtain simulated time series from specified models. Such simulations are useful for comparing experimental observations of real-world systems with the latest notions of how a gene regulatory network might function. The ability to quickly explore such dynamics is pivotal to many analyses in computational biology.