Tanaka, Masahiro, Tomio Kakuyama, and Madoka Takada Urhausen. 2003. "Drawing and storytelling as psychotherapy with children." In Handbook of Art Therapy, edited by Cathy A. Malchiodi, 125-138. New York: The Guilford Press.

In this paper, the authors argue that children in psychotherapy often have difficulty expressing their feelings and concerns verbally. In this circumstance, storytelling is an effective intervention to assist children in verbalizing their feelings safely (Tanaka, Kakuyama, and Urhausen 2003, 125).
        The authors introduce two art therapy techniques, egg drawing, and cave drawing, both of which work for stimulating the active imagination of the child and motivating the child to engage in artistic expression and storytelling through specific directives and guided imagery (123). Especially in the cave drawing, as a metaphor for a safe place, the cave functions to set boundaries between real space and therapeutic (pictorial) space (135). 
        It concludes that art therapy as it allows non-verbal communication, can be a complement to verbalization, and even assist children in verbally expressing their thoughts (136). Furthermore, the use of drawing is helpful to children with emotional problems. “The combination of both drawing and storytelling, along with the therapeutic relationship, provides a way for troubled children to express their fears and anxieties through the safety of projection and, in the case of art, nonverbal expression (137).” At last, the goal of therapy is not to complete the art expression or story, but to make the transition of the phases smoothly and thereby bring continuity to underlying themes during the course (136-137).

Reed, Aaron A. 2017. "Changeful Tales: Design-Driven Approaches Toward More Expressive Storygames." Ph.D. diss., University of California, Santa Cruz.

In this thesis, the author discusses collaborative storygames in one of the chapters. Reed defines a collaborative storygame as a playable system with units of narrative in which some or all the contents are created during the play by participants, and that creation is mediated by the system designed to produce a compelling story (Reed 2017, 290-291). 
        Reed divides participants’ actions in collaborative storygames into four categories: Generating, Storywrighting, Negotiation, and Administration (304). Generating is a key part of collaborative storygames. The generated ideas perform as building blocks of stories and game playing. They can be created by players during play, but the pre-written elements such as backstories, character classes, or a set of rules are also important for making the fantasy more concrete and specific (304-305). Storywriting is a process of combining ideas from all participants in elegant ways to tell a story–choosing what to place in it and how what’s been put there is meaningful. The crucial point is that people yearn to fill in the gaps between narrative fragments, to make them into a coherent story even (or especially) when they seem contradictory (305). Negotiation is a process of determining which possibilities actually happen in a story, and again, when contradictory ideas occur, there must be a process of resolution by which all participants can agree on a single imagined story space within which play can continue (306). At last, Administration provides rules that regulate the actions of continuous activities in time and form, which may also include how participants take part in or respond to the activities. 
        Reed takes examples to discuss some specific features and mechanisms that collaborative storygames may have. For instance, in Tale of the Crystals, released in 1993, an early adventure narrating game through an audio cassette tape, the audio story narrates a problem for players to resolve. The solution is to be freely discussed between players. It also divides players into different roles so that they can have distinctive performance in helping solve problems and creates a scenario of collaboration (286-288). In 2007, interactive fiction designer Andrew Plotkin created an untitled game, in which two players write in the same fictional journal but from two different time periods: one from a long-dead civilization at the height of its power and the other as an explorer finding the journal in its mysterious ruins. The designer created a simple currency and exchange system allowing two players to respond to each other’s story and elements. The currency also functions as a way to maintain an equal creative power between players and to give the story an approximate length (308-310). In Microscope, a history timeline creation game released in 2011, players take turns writing events on index cards. It is called a minimalist collaborative storygame, in which the generation of ideas is entirely up to the players but not the system. The players have complete authority over their own creations, they build events on their own, and they collaborate through the medium of the game but not through open discussion and conciliation. This rule ensures that each player has an equal say in creating the world and forbids socially aggressive participants to dominate. The game designer says, “If you collaborate and discuss ideas as a group, you’ll get a very smooth and very boring history. But if you wait and let people come up with their own ideas they may take the history in surprising and fascinating directions (311-313).”