Artificial LIfe ENvironment (ALIEN) is an artificial life simulation tool based on a specialized 2D particle engine in CUDA for soft bodies and fluid-like media. Each simulated body consists of a network of particles that can be enriched with higher-level functions, ranging from pure information processing capabilities to physical equipment (such as sensors, muscles, weapons, constructors, etc.) whose executions are orchestrated by a signaling system. The bodies can be thought of as agents or digital organisms operating in a common environment.