To be determined..
Two players take turns in placing items in the game world. Items either attract animals, or drive them away. They try to get 2 animals together, either to make them mate, or to make one eat the other. Each player has a limited number of items, and both players have conflicting goals. The goals always relate to the animal population. Whoever fulfills his goal better wins.
Each player owns one kind of animals, and there is a third kind, which is not owned by anyone.
Players can select from their available items, and place them in the game world. If they have caused animals to breed, then they can place the offspring in the game world. This works entirely by mouse (or could work with a touch-screen). If the game world does not fit into one screen, then players also can scroll across the game world.
All animals act in each player's turn. The player's animals move first, then the neutral animals move, and then the animals of the opponent move. Within each of these sets the animals move “simultaneously”.
The game world is a 2D square seen from above, divided into a grid. Fields of the grid may be blocked, passable, only passable by one type of animal, or temporarily blocked. A field can be occupied by one animal, or one item. Except for players placing items the game world is not modified. Upon start the game world contains animals and items.
There are 3 types of animals.
Animals have a sight-range, within this range they notice items, and other animals.
Initially, they can breed once with animals of their own kind. When they breed, the player that made the last move must place the offspring, within the sight-range of one of the parents.
They kill & eat animals of one other kind when in sight-range, and are in turn killed & eaten by the other kind. After eating, they move to the position of their prey and can breed one more time. If multiple targets are in sight-range, the closest is chosen, and ties are broken using a deterministic rule. Animals eat only once per turn.
Per turn, an animal is only affected by one item. Which item affects it is determined by a deterministic rule. I.e. an animal can be attracted into the range of a shoo-item, or vice versa. The animal will not react to the second item in the same turn.
Items block the field they occupy. Items can be placed only on fields that are passable and not occupied by something else.
The attract-item causes the closest animal of the animal type affected by it to move as close as possible to the item. The item must be close enough for the animal to notice it. If the animal can reach the attract-item, then it destroys the item and takes the item's position. If several animals have the same distance from the item, then a deterministic rule is used to determine wich animal will be affected.
The shoo-item causes all animals affected by it to move away from it in the direction one gets by drawing a line between the item and the animal. The animals try to move as far in this direction as is necessary to get the item out of their sight-range. If this is not possible they will search for a position that gets them out of range by a deterministic rule.