The rats are some of the most common enemies in Dark Castle, they appear in almost all the levels, and show up in Dark Castle, Beyond Dark Castle, Color Dark Castle, Dark Castle Mobile, and Return to Dark Castle.
For killing a Rat you get 20 Points.
Main Article List of Plagued Enemies
This is one of the enemies in the game that wont kill you as long as you are carrying an Elixir. If you are carrying an Elixir, then it will simply make you lose one elixir.
In the original Dark Castle, if you touch a rat without an Elixir, then you will die. In Beyond Dark Castle, and Return to Dark Castle, if you touch a rat' when you have no Elixirs, then you lose health, until you stop touching it.
The Rats have stayed looking the same since the original Dark Castle, with the only real changes being color.