This is a particle zoo. It consists of all the fundamental particles that we know of. You will notice two things, which are particles (but in real life they don't have faces) when you start the project. Hover over one of the things to see what it is. Then, in the top left corner, it will say what the particle is. Click on one of the particles to change it. When you click on it, the particle will start to drift away, and in it's place is a new particle. You can hover over the new particle and it will once again say what it is in the top left corner. Click on the new one to once again change it. You can tell which particle are the old ones and which are the new ones. The new particles don't move, but the old ones drift around. You can keep clicking on the new particles for as long as you want.
I added Graviton and Axion AKA Dark Matter. Tachyons are just sped up particles, the only thing different about them is the speed.