Hello again guys, I wanted to ask, what is the best way to create a realistic explosion for video games? What are the step to follow and the software to use? I know it's a pretty big question but at this point I cannot find any good tutorial except for creating one using asset packs and I don't want that. I want to create it by myself from scratch. Currently I am using After Effects (which I am still a novice with), then assembling particles in Unity and I don't like the output that I am receiving.

I created explosions mostly for 2D games, but I might have a few suggestions for you.

Use some sort of fire sprites for the actual explosion. Define an area where your fire sprites shall be emitted. When creating the explosion, burst a few particles with the fire sprite inside the area. Depending of the game, the area should be 2D or 3D.

Use a mix of smoke particles with fire particles which are pretty much flying straight away from the explosion.

Play with the lighting. Explosions are pretty bright, so you could set a light source where the explosion is.

Use as much particles as possible (even for the fire). 

Last but not least: Use references. Check out a few games with great explosions, learn how they are built up, try to copy them. Even try copying more than one explosion.

Hope it will help you with your work.

Cheers,
Lukas