The paper discusses the goals, design, models and implementation state of a new discrete-event simulator of computer networks. The Integrated Network-Environment Simulator (INES) aims at creating a suitable simulation tool for the evaluation of network algorithms and protocols operating on a virtual environment. This feature makes the simulator particularly useful for testing MANETs, VANETs, WSNs, situated communications, and other algorithms or technologies with realistic situations where the environment could significantly affect their operation. INES uses mesh geometries to model the objects of the desired environment, which may restrict node roaming and affect wireless communications during a simulation execution. Complementing INES development is the implementation of the Packet Animator, which can visualise INES traces through an OpenGL-based animation engine. Finally, the paper discusses examples that make use of the mobility and communication models currently supported by the simulator.