This repo contains a Java implementation of an ecology multi-species interaction game/simulator. The purpose of the game is nothing more that provide a framework to model how relatively simple interactions between a few types of organisms can produce complex patterns and dynamics. This simulator is loosely inspired by the classical "Game of Life" - a mathematical 2D model that produces complex behavior from a set of extremely simple rules. My version of this concept lacks this simplicity, but instead features much more realistic creature movement, reproduction, movement, growth, interaction, and supports multi-species interactions such as predation, resource competition, sun shading, biomass distribution modeling, and others.

This is just a fun passion project I came up with as I was learning Java. In its current form the project has no real scientific value. However, since the game I built supports fairly complex interactions and extremely efficient for large-scale simulations, this game can theoretically be used to build a much more realistic microbial interaction simulation.

This game has turtles that eat ladybugs, elephants that are the size of butterflies, and plants that don't need water... No, its not realistic. I just used graphics and creature statistics that I thought were fun. The underlying core inter-species competition and predation mechanics are quite real, however.

The entire simulation and visualization is build from the ground up in Java. The coding implementations used throughout the project are low-level and carefully thought out with speed in mind. The final processing and rendering time complexity is O(n), and memory is also O(n), which was quite difficult to achieve considering the complexity of the interactions. Here are some of the simulation's features:

1. Every creature (bug, tree, grass, etc) is processed independently every frame (running at 60 frames per second). This means 60 times every second, a given creature does all the things it can do at that moment, including: move, accelerate towards something, run away from a predator (animals only), investigate the surrounding around, hunts prey (animals only), eats, grows, reproduces, lays eggs or spreads seeds, and shades neighbors (plants only).
2. A novel custom implementation of a multi-threaded Quad Tree 2D search allows all the creatures to "see" all other creatures withing vision range in real time with a total time complexity of T=O(log n), which allows me to simultaneously calculate complex interactions between hundreds of thousands of organisms.
3. Full multi-threading support - all steps of the simulation are done in parallel to improve performance. With 12 cores I am able to simultaneously render and display ~100,000 organisms while maintaining a 50-60 frames per second refresh rate.
4. Low-memory optimizations. The project uses pointers and some clever efficient memory caching throughout to be able to store millions of loaded organisms, each with their current parameters, movement, animations, etc.
5. Because the game allows for fast scrolling and zooming but can only realistically process ~250,000 creatures at a time, it saves creatures that are very far away from the player's current position into indexed bins. Creatures stored this way are not updated while the player "is away", but will spring back to life if he/she returns to that location.
6. The field gets randomly populated to create the initial populations, however as the observer scrolls or zooms to previously un-initialized locations, the program will procedurally generate new populations to roughly match those that were previously on-screen.
7. All rates (i.e grows, speed, acceleration, etc.) in the game are handled with the current frame rate in mind, which means the simulation will still work the same with tens of millions of creatures (it will just look more choppy).
8. Each creature supports animations, as long as you have PNGs of each frame. As the creatures grow and move around the images are automatically rotated, resized, change opacity, etc. (all done in O(1) time thanks to caching). However, since I am not a digital artist the only creatures that are currently animated are the butterflies.

1. Grass: the smallest plant in the system. Very fast-growing, but is easily shaded out by larger plants. Eaten by elephants. Generally, grass will go extinct if it becomes out-competed for space.

2. Bush: the medium plant in the system. Fast-growing and prolific. Shades out grass and smaller tree saplings. Eaten by caterpillars.

3. Tree: the largest plant. Slow-growing but has a large canopy that shades out all other plants except the strongest of adult bushes. Will slowly cover the whole map unless kept in check by beetles.

4. Beetle: a quick bug that rapidly eats trees while young. Once an adult it stops eating and searches for new trees to lay eggs under, which it does until it starves to death. Is predated on by turtles.

5. Caterpillar: the larval form of the butterfly. Very slow-moving and has poor senses. Eats bushes until it is fully grown, at which point it turns into a pupae. Both the caterpillar and the pupae are predated on by the turtle.

6. Butterfly: the adult for of the caterpillar. Moves very fast thanks to flight. It does not eat, and will fly around laying eggs on new bushes until it starves to death.

7. Elephant: a large last herbivore that eats grass. It is slow to reproduce but can survive food shortages.

8. Turtle: the predator of the system, hunting young and adult beetles, caterpillars, and butterfly pupae. Is very slow and vulnerable when young.

Once you install the Java application and run LaunchGame the game will launch, randomly populate the world with some creatures, and fast-forward a little to a point where the populations become more stable. From there you can observe the simulation and interface with it using the following controls:

1. Use "W", "A", "S", and "D" keys to scroll up, left, down, and to the right (respectively).
2. Use "-" and "+" keys to zoom out or zoom in on the field.
3. Press the space bar to speed up the simulation. This part is really fun.
4. Press "R" to take a screenshot, or hold "R" to save many frames to make an animated GIF later. The frames/screen shots will be saved into saved_images. Note that this drops the FPS.
5. Use the mouse to select the creature icons in the bottom right and then left-click on the field to place new creatures. It can be fun to mess with established communities this way.

Note that you will need to recompile the code (see installation) to incorporate changes.

Most of the important constants and options for user/window interaction (panel size, zoom speed, etc.) can be configured in src/game/constants/UiConstants.java. Options for controlling animal and plant parameters (growth size, speed, reproduction, size, animations, etc) can be found in corresponding files in src/game/things/AnimalConstants and src/game/things/PlantConstants. Options for the plots and numbers shown in the dashboard can be changed in src/game/constants/Dashboard.java.

If you would like, you can create your own creatures by following the template examples in src/game/things/AnimalConstants.java and src/game/things/PlantConstants.java, and adding your new creature constants to src/game/world/InitThing.java. I would recomend making a copy of another organism and gradually changing it.

This is simply a Java project, so if you are comfortable, feel free to build and test however you prefer. The only "special" dependency is that the game needs to be run inside GameOfLifePlus/ so it can have access to GameOfLifePlus/graphics and GameOfLifePlus/rendered_images. You will obviously need JRE installed on your system. You can also load the project up into an IDE and launch src/LaunchGame directly.

Note: the first time you launch the game it will need to generate all intermediate rotation/opacity variants of the creature images, which may take a minute. In all future runs the game will load these from disk, which only takes a few seconds. This will take extra memory, so I recommend giving java some memory to work with (like this: java -Xmx8192m -jar runGame.jar).

Alternatively, just follow these steps (for Mac/Unix):

# install Java with conda
conda install -y openjdk java-jdk

# clone the repository
git clone https://github.com/ursky/GameOfLifePlus.git

# compile the code
cd GameOfLifePlus
./installGame.sh

Then to run the game:

./runGame.sh  
# OR
java -Xmx8192m -jar runGame.jar 

This game was independently developed by Gherman Uritskiy.