In Criminal Case, the player acts as a detective to solve murder cases, locating relevant clues at crime scenes by clicking items in the scene. Rapid clue location is rewarded with greater scores; the player earns stars that can later be used as a type of currency for performing necessary tasks such as examining evidence and interrogating suspects. At the conclusion of every case, the player is presented with all the suspects and must arrest the one who fulfills each of the criteria gained throughout the investigation. If the decision is correct, the case is solved. To unlock the next case, however, the player is also required to complete the solved case's post-indictment chapter, enabling the player to receive reports and finally move on to the succeeding case—though this procedure does not have to be undertaken in any of thetutorialcases. There are also puzzle elements and various progression and bonus features integrated into the game.
Initially presented as a university study group started by Rozetta Pierre, Ad Astra is a group of people who consider themselves to be superior and intelligent over the general population. Comprised of Rozetta and her peers, each Ad Astra member had become influential in their respective fields in a bid to gain domination over the city and the world. The police discover Ad Astra's existence while investigating Rozetta's past to gain information on her plans post-arrest.
They eventually learn of the existence of Ad Astra's junior faction comprised of currentstudents in the University, which had been instructed to kill Rozetta's mentor, Kevin Charles, to prevent him from telling the police about the identities of the members of the original group. After bringing down the junior faction, the police gain a lead that leads them to discover and stop Ad Astra's plans of dominating the city by poisoning the city's crops. The fight between the police and Ad Astra only becomes more intense from here, with the team slowly uncovering the identities of Rozetta's peers, one of the team members being sacrificed, and Ad Astra trying to execute a plan ominously named "Plan Supernova."