# Biome Generation Tool: A Mixed-Initiative Software for the Procedural Generation of Biomes
## 2 Literature Review  
Mixed-initiative content generation covers a wide range of systems in which a human creator and a computational creator interact to produce new content [12]. The amount of initiative and impact of the computational side can vary wildly between systems, from light assistance to almost complete independence. However, the software should be a proactive co-creator rather than a tool that merely reacts to user input [13]. This study focuses on tools in the middle of this spectrum, promoting human creativity rather than simply providing assistance [14]. These tools allow creators to be both productive and innovative [15] while avoiding potential risks of fully autonomous PCG, such as repetitive or unplayable content. Out of the vast amount of published mixed-initiative tools for content creation, some of the most relevant applications using Evolutionary Algorithms (EA) include the following:* **Sentient Sketchbook**: One of the first examples of the use of EAs in mixed-initiative tools is Sentient Sketchbook [9]. Sentient Sketchbook is a tool for creating maps supported by an EA that evaluates the current state and suggests modifications to assist in the process and inspire the designer. With this tool, users can edit low-resolution abstractions of maps with four different elements: passable tiles, impassable tiles, resource tiles, and player bases. The map is evaluated regarding resource safety, safe area, exploration, resource safety balance, safe area balance, and exploration balance. For each one, the tool displays a playability statistic, a map suggestion that maximizes said statistic, and another six suggestions that maximize diversity through novelty search. The tool updates both the statistics and suggestions each time the user performs a change. The suggestions are generated by a two-population EA using a feasible-unfeasible approach. Each population contains 10 chromosomes and runs 10 epochs before selecting a solution. Research concludes that an EA with a feasible-infeasible two-population paradigm [16] is more robust than the other state-of-the-art novelty search approaches of that time for finding feasible solutions. It also states that the tool shows potential due to the usefulness of the suggestions and feedback provided to the designer [9]. * **Baba Is Y'all**: In recent research, use of EA can be seen in a mixed-initiative tool to create maps for the game Baba is You. This study aims to provide a tool where multiple users can interact with a PCG system to create content. Baba is Y'all [6] is a web service tool that allows users to edit, test, evaluate, and upload levels for the Game Jam version of Baba is You. The tool uses an EA to suggest modifications to the user using previously created maps stored in the cloud, including those uploaded by other users, as chromosomes for the initial population. The tool has a Generation Module that can be accessed at any time by the user. This module allows the user to change the variables of the EA, such as the stopping criteria, mutation rate, and initialization method, to customize the EA without changing the algorithm's inner workings. The objective of the EA is to evolve towards diversification and fulfillment of missing requirements on the map. The results of the research were promising but hampered by the lack of maps in the tool cloud and the difficulty of the learning curve. Nevertheless, it worked as validation and a guide to proceed with the efforts to keep working on the tool. * **Evolutionary Dungeon Designer**. Another project in this field focuses on the subject of map creation in rogue-like games [7]. This research is the expansion of a previous one in which the topic is a mixed-initiative tool for creating rooms in rogue-like games [17]. Evolutionary Dungeon Designer (EDD) is a mixed-initiative tool for the creation of dungeon rooms in videogames. The tool provides an interface where users can edit, generate, save, and load rooms.