For the gameplay, I was inspired by the Ace Attorney and Danganronpa series, as both allow the player to solve murder mysteries interactively while also having a strong focus on story and dialogue.

However, I made major changes to the formula in order to offer a varied and immersive gameplay experience that fits my vision.

I wanted the gameplay for the crime scene investigations to be free, open and non-linear for the sake of immersion and giving the player the feeling of truly being in control of their own investigation and exploration.

Therefore, I decided that from the start of each investigation, the player would be able to go to all relevant places, talk to all relevant characters and pick up all relevant items in the order they want. The only exception would be unlocking new dialogue with characters based on previously found clues, for example when the player shows a piece of evidence they discovered to a witness.

The player would get the option to end the investigation and proceed to the discussion phase at any time, but would be prevented from doing so by their investigation partner if they were still missing necessary clues.

Naturally, Ace Attorney's cross-examinations and Danganronpa's endless debates were inspirations for Circle of Suspects' system of interactively solving crimes using the previously found clues. However, I wanted to offer a larger variety of puzzles and avoid the problem of the player having the right idea but being unable to express it that is common in such games.

Therefore, I came up with the Train of Thought system.

Similarly to other games, another character expresses their logic or testimony as a chain of short statements. The player can interrupt them at each statement and then gets dialogue options for a comment to make on this statement, which can result in unlocking new statements or even changing the path that the rest of the conversation takes entirely.

What dialogue options there are varies between each discussion segment in order to create a variety of puzzles - they can be asking further questions, answering questions, pointing out problems or providing evidence.

For example, there is one puzzle where the player has to choose whether the culprit or the victim locked a door, each unlocking a new chain of statements.

The player then needs to go through both chains, which can be switched at will, and prove each statement impossible with evidence in one, while proving each statement possible in the other.

When designing the murder mystery, I started by coming up with the main trick the player would have to figure out. The trick was designed to be only possible in this specific setting and allow for a surprising plot twist.

I then built a timeline of the murder around this trick and made a list of clues it would leave behind.

To get inspiration for how to help the player solve it, I did roleplaying sessions where other people, unaware of the solution to the mystery, would have to solve it based on clues I gave them.

I then created and described each puzzle in the game design document.

At one point, there are many contradictions between all of the witnesses' testimonies and it would help solve the crime to find out what these contradictions have in common, so I designed a minigame where the player has to compare testimonies and select which of certain aspects are contradictory and which are not.

I began writing the story by creating the characters.

As the story at its core stems from the relationship between protagonist Riley and her friend and investigative partner Torin, the most care was put into developing these two characters, their unique personalities and outlooks on investigating as well as the relationship between them.

For each other pair of characters, I took notes on how they would feel about and interact with each other as well.

Other than this pair, the most important relationships where those between the murder victim and the other characters - for the suspects, because it is relevant to their potential motive and for Riley, because her having a very good relation to the victim makes the case feel more personal and gives her a stronger drive to take charge of the investigation.

While working on the characters, it was also important to flesh out the futuristic setting and the various alien species beyond the constraints given by the mystery.

When I was done designing characters and puzzles, I used the game design document as a reference and wrote a screenplay containing all the dialogue in the game as well as how the player triggers it. Care was taken to give each character a unique style of dialogue.

For more player interaction, freedom and enjoyment, I also wrote a large amount of optional dialogue that can be explored:

While the entire screenplay stands at roughly 75000 words, which would translate to about 300 pages in a novel, some players that skipped most optional content only needed about 3 hours to finish the game.

For the investigations, I wanted point-and-click gameplay where the player can click on objects to interact with them, these objects ideally being highlighted when hovered.

As Ren'Py is an engine for visual novels with dialogue options usually being the only interactive gameplay, there is no simple function for this type of gameplay.

It does, however, allow creating custom screens that can contain imagebuttons, so I used these for point-and-click gameplay, the interactable objects being imagebuttons on top of the background.

Creating a screen for each investigation location would have been inefficient, however, as there are many locations with many variations throughout them game.

Instead, there is only a single investigation screen defined in Ren'Py, which takes the name of the location and its variation as parameters and then loads the information on which buttons to place and where they lead from a Python dictionary defined elsewhere:

On top of visual novel and point-and-click gameplay, Circle of Suspects has an inventory that evidence and character profiles are stored in. Tutorials for RPG inventories in Ren'Py are publically available and I some of them as a template.

Then, I had to make quite a few changes to account for my game's specific needs, such as:

I came up with solutions to all of these problems from scratch.