Mixed-initiative story co-creation with TaleMaker

Most storytelling games bring people together to co-create stories. However, they often require considerable creative effort and skills from all players, possibly discouraging less resourceful participants and impairing stories' quality. Moreover, most stories created within these games are usually only kept in players' minds rather than on storage, despite being a valuable and original asset, with a large potential for the narrative research community. We address these challenges with a novel mixed-initiative approach aimed at supporting a group of players to incrementally co-create a story, one sentence at a time. Our method features a hand generator offers a unique set of tokens (words) to each player in each turn. This generator carefully combines tokens relevant to the ongoing story, to each individual player, to the group as a whole and random. We implemented this method in TaleMaker, a multiplayer online game that stimulates playful co-creation of a story. TaleMaker gives players considerable creative freedom to compose their sentences, combining a gentle structural steering with the wisdom of the group to determine the best direction for the story. The collected output of TaleMaker consists of annotated stories, with slots (e.g. action, character, location) filled with words associated with a WordNet synset. From a preliminary evaluation, players reported that TaleMaker effectively stimulated story authoring, and perceived TaleMaker-created stories of considerable quality. In addition, a first analysis of the collected tokens confirms that players mostly collected story-related tokens, rather than those randomly offered.

TaleMaker features both competitive and collaborative elements, designed to provide a playful experience while co-creating stories. In each turn, each player collects tokens and uses them to compose a sentence that is compelling enough to convince other players that it belongs in the story. Then, all sentences are submitted for a voting round, where the most popular sentence is appended to the story and its author is rewarded. In most steps, players are under time pressure, to keep the tempo, add to the competitive gameplay, and avoid long waiting times. The game concludes when the majority of players decide to end the story, and its title is then chosen.

TaleMaker is played online on a computer or a mobile device. In order to play, players need to create a game room which can accommodate two to eight players. No limitations exist as to whether people choose to play co-located or remotely. Moreover, players will always be able to join and leave the room at any time, although the room remains open until the story is completed or after a prudent period of idle time has passed. Any player may join a public game room during an ongoing story. This facilitates the flow of new ideas into the story. In addition, one can also create a private game room, accessible only with a secret code.

The core game loop of TaleMaker consists of 8 basic phases: (1) creating a story prompt, (2) selecting piles (categories) of tokens (words), (3) collecting and/or discarding tokens, (4) composing a sentence, (5) submitting and voting for the winner sentence, (6) receiving rewards and rankings, (7) voting whether the story should end, change location or continue, and finally (8) writing and voting for a title.

The main goal of the hand generation method is to strike a balance between supporting creativity among players and maintaining the competitive nature of the game. For this, in each turn, each player receives a collection of tokens (the served hand) from which they will retain a subset (the collected hand), to be used when composing a sentence. Tokens in the served hand are sampled from five distinct bags of ranked tokens, each of which is designed to promote players' creativity and story quality in different ways. These bags hold an ordered set of tokens that are ranked based on relevance or relatedness to different aspects of the story and the game. The purpose of each bag is summarized as follows:

• Related Bag: consists of tokens, ranked by the degree to which they are related to other tokens in the story. This bag allows players to keep the context of the story consistent. For example, an island is typically associated to tokens such as coconut, swim, sand, shipwreck, etc.
• History Bag: consists of only the tokens previously found in the story. This bag enables players to stay on topic. The story might contain objects of narrative importance, for example, a treasure map; therefore, it is convenient to offer the token again, so that players can further develop the story using it (e.g. what happens to the treasure map?).
• Player Bag: includes tokens ranked according to their predicted relevance to each individual player. This bag is intended to support players' creativity and planning. For instance, a player planning sentences in the context of a love story, might collect tokens such as love and kiss; that player might then wish to receive other relevant tokens, such as hug, gift, date, etc.
• Group Bag: includes tokens ranked according to their predicted relevance to the whole group. With this bag, players are encouraged to consider the previous contributions of others. For example, former sentences that did not get approved, might still contain tokens that are relevant to the present part of the story.
• Random Bag: includes all possible tokens, sampled in a random manner. This bag aims to stimulate players to think creatively about seemingly unrelated tokens, possibly coming up with new associations or story directions.