FlightGear Flight Simulator: free open-source multiplatform flight sim
A circuit simulator with graphical user interface (GUI)
Sky simulator for Ascom using an artificial sky or online DSS images.
X-Plane plugin that displays a tablet to aid VR usage
VHDL 2008/93/87 simulator
Fast PlayStation 1 emulator for x86-64/AArch32/AArch64
Simulate chemical processes using advanced thermodynamic models
PICSimLab is a realtime emulator for PIC, Arduino, STM32, ESP32, ...
Component, CA, and CCA models; superdense time, DB repo, testing, etc.
An advanced network simulator to design and configure virtual networks
Soft-body physics simulator
Real Time Electronic Circuit Simulator.
mod_RSsim Fork with Updates
A Bee Swarm Simulator macro for Windows
Virtual Pipe Organ Software
Data Compression Simulator for E-Learning:
Android, UIQ 3.0, Series 60 Edition 5 open-source software
Highly-Experimental Playstation Simulator x64
Air traffic control tower and radar simulator (solo + multi-player)