Castle Mouse 2000 is an old Mac puzzle game. The goal of the game is to scare a mouse into a hole. The game takes place on a small tile grid of around 10 by 10. On this grid are small animal sprites each taking up 1 cell. There is a progression of animals ranging from small to large: mouse, cat, dog, etc., all the way up to lion, bears, and an elephant, probably though I don’t remember all the animals. The animal of one larger size when adjacent to the smaller animal scares that animal in the opposite direction. The elephant can also be scared by the mouse.
As a puzzle game it is very interesting somewhat similar to the game Rush Hour, the game where you slide blocks out of the way in order to clear a pathway. Though, not quite the same, as you are given a setup and asked to add pieces that will allow the mouse and any other animals to interact in a simulation.
There must be some rules about blocking and stopping animals. I seem to remember say a cat bordered at some distance by two dogs that would move back and forth like a trap. What if this animal was blocked in its motion by another animal that did not interact with it? If that animal clears the area where the cat moves back and forth, does the cat continue to run in the direction of the opposite dog for eternity? I also remember that when two animals collided at the same cell in the sense that the movement animation would cause them to overlap in that next instant they would bounce backwards the path that they came. I think it is possible that when an animal is blocked it just stops and will not continue to move once its path is cleared. This allows the option of another animal changing the direction of the once moving animal sometime down the line.
Let me cook up an example of a puzzle with numbers denoting the animals of different sizes, 1 being the smallest, and 0 giving the hole.
0....1. 5...... ....... ......2 .3..... Place 4
On this small grid, where the periods are spaces, by placing the 4 underneath the 5, on pressing go, the 4 will be sent down to the 3, the 3 sent to the right, the 2 up and the 1 sent to home, resulting in the following outcome.
0.....2 5...... ....... ....... 4.....3