I've seen Ctype being mentioned and being a major thing in saves, but I don't understand what it is. Can someone explain?
It is the element put in parentheses in the HUD next to the name of the element of the particle your cursor is pointing to. For example, SPRK (METL) means the particle is a spark with ctype metal. Ctype is used by the game to store information about a particle. For example the Ctype of lava determines what it will freeze into and ctypes of snow and ice determine what they will melt into. Many other elements use Ctype for different things. Using console commands or the prop tool you can modify this property to get interesting results. Life, tmp, and tmp2 are also used to store different data, and people manipulate them to do interesting things.
Ok, thanks! You've cleared up a lot for me.