Simio is described as 'is rapid modeling, discrete-event simulation software'. There are six alternatives to Simio for Windows, Linux, Mac and Raspberry Pi. The best alternative is Anylogic. It's not free, so if you're looking for a free alternative, you could try JaamSim. Other great apps like Simio are FlexSim (Paid), WITNESS (Paid), SIMUL8 (Paid) and Simile (Paid).
AnyLogic is a cross-platform multimethod simulation modeling tool developed by The AnyLogic Company (former XJ Technologies). It supports agent-based, discrete event, and system dynamics simulation methodologies.
WITNESS is an established dynamic process simulation tool used by thousands of organisations to validate a proposed facility or business process, to achieve a desired process performance metric or to support continuous process improvement activities.
JaamSim is a java-based free and open source discrete-event simulation software which runs on Windows, Linux, and Mac OSX and includes a drag-and-drop user interface, interactive 3D graphics, input and output processing, and model development tools and editors
JaamSim vs Simio opinions
pros, cons and recent comments
Free, zero installation required, no limit on number of simulated objects
Multi-paradigm modelling and simulation software for complex dynamic systems in the earth, environmental and life sciences. Logic-based declarative modelling represents the interactions in these systems in a clearly structured, intuitive way.