syfluid is a funny toy as well as a real simulation. It simulates a fluid or a gas in a very colorful, graphic, and psychodelic way. Drag while your right mouse button is pressed to "draw" the fluid or density field. Drag while your left mouse button is pressed to make the whole thing move, i.e. to "draw" the "forces" that you're adding to the fluid or density field. Press "r" to clear the screen and "m" to open the menu. syfluid is written in C++ using OpenGL. Even though it is heavily performance optimized and using OpenGL Shading Language (GLSL), it is a performance hog. Use "f" to show the FPS. If they are lower than 30, then reduce the quality parameter that you find in the menu from 200 to e.g. 100.