FlightGear Flight Simulator: free open-source multiplatform flight sim
The A32NX & A380X Project are community driven open source projects
An implementation of a quantum simulator that you can run locally
Simulate chemical processes using advanced thermodynamic models
An advanced network simulator to design and configure virtual networks
Ab initio simulator for thermal transport and lattice anharmonicity
Circuit simulator for power electronics
A simulator for drones, cars and more, built on Unreal Engine
PySCeS is the Python Simulator of Cellular Systems
Modbus slave simulator
Small factory simulator for control logic test purpose
Simulate high power rocket flights with splash down plots
A tool able to simulate gene-environment and gene-gene interactions.
Bayesian Adaptive Trial Simulator
Controller-Pilot Data Link Simulator for procedural and radar training
YASimCommander is a platform-independent editor for YASIM files.
Robot simulator inspired by Sim.I.Am
Multiscale Neuroscience and Systems Biology Simulator
TCAD Device Simulator
A collection of useful tools for astrophotographers
action/combat flight sim
BlueSky Open Air Traffic sim, (Windows/Linux/Mac, Python 2.x based)
A Turing Machine Simulator