FlightGear Flight Simulator: free open-source multiplatform flight sim
Virtual X-Ray Imaging Library on GPU
Measurement and Automation Framework + Tool
Object-oriented equation-based modelling and optimisation software
Interactive geometry software for Euclidean and non-Euclidean spaces
Real-time interactive 3D graphics API for scientific simulations
Antimony is a human-readable, human-writable model definition language
A framework for simulating open quantum dynamics
PPface is vector processor emulator / simulator
OpenM++: open source microsimulation platform
A multi-modeling and simulation environment to study complex systems
Fancy interactive fluid simulation for gfx fans, VJs and demo coders
A framework for implementing real-time control systems
The functional model of the old calculator series Wang 700 and 15VSM
Simple ball collision simulation in C++ SFML
Neural Network Engineering Platform
A particle simulation visualization program
Simulator of 8051 microcontrolers