Achieving more focused and accurately controlled stimulation has been a trend in electrical stimulation over the last few years. By simultaneously stimulating adjacent electrodes, a more controlled electrical field can be created. This has led to a growing complexity in stimulator hardware and generation of stimulation patterns. Designing and tuning the devices is a complex problem that can be addressed with simulations. We propose a graphical, open-source software to simulate complex neural stimulations, and discuss the design and use of the software. Finally, we present some simulations performed with Gom2n to illustrate its capabilities and performances.