The gameplay in Dearly Stars is similar to previous games in the series, but with new elements and differences to the minigames.

The story is told from the perspective of Ai Hidaka, Eri Mizutani and Ryō Akizuki—three prospective pop idols introduced in Dearly Stars as they enter the talent agency 876 Production, and deals with their training on their way to stardom.

Dearly Stars is a life simulation game in which the player assumes the role of one of three pop idols at a time: Ai Hidaka, Eri Mizutani or Ryō Akizuki.

This gives the player a guide on how to gain popularity by augmenting an idol's statistics via the choice of song they will perform and what costumes they wear during an audition.

The lessons are in the form of three minigames which serve to increase or decrease an idol's statistics in either vocal, dance or visual image.

[1] The promotional phase of the gameplay mainly deals with the idol conversing with various other characters and doing events, some of which are necessary to progress the game.

[2] Depending on which choice is made will effect how well or poorly the communication is received, which results in either bad, normal or good memories.

[1] A bad memory will decrease an idol's enthusiasm, which is displayed at certain points throughout gameplay by a horizontal bar in the top-left of the lower screen.

The ranks continue from D to C, B, A and finally S. Each of the three scenarios follows a branching plot line with multiple endings, and the story's divergence mainly depends on whether an idol passes or fails an audition,[3] though this is not always the case.

[3][4] In the game's stage mode, the player is able to freely customize a stand-alone performance, including options for the song, costume, accessories, choreography and camera positioning.

[1] Dearly Stars occurs prior to the events in The Idolmaster 2, and revolves around characters related to the talent agency 876 Production (876 Pro), a rising studio located in a small office.

The three main characters are Ai Hidaka, Eri Mizutani and Ryō Akizuki—three prospective pop idols introduced in Dearly Stars.

[9] It was announced in May 2009 as the first game in the franchise's next stage called "2nd Vision", which was described as The Idolmaster's next project that would further expand the series' world.

Tanaka would go on to say that the scenario in Dearly Stars would not have worked without having a different company president—in this case, the president of 876 Pro, Minori Ishikawa.

[9] For the dance sequences during performances, Kujioka chose to employ talent star Fumi Sakura, as opposed to professional dancers who had been used in The Idolmaster games up to that point.

Also, because of the idols in Dearly Stars are young and are just starting out, Kujioka told Sakura to purposefully mess up some dance portions to reflect this inexperience.

[13] Despite The Idolmaster originally being targeted at a male audience,[14] there were also advertisements and promotions for Dearly Stars geared towards young girls.

[19] Dearly Stars features 10 songs the idols perform[3] written and composed by a variety of songwriters.

The chief music director Kōji Nakagawa told Satoru Kōsaki, the composer of the game's theme song "Hello!!

"[9] It was decided beforehand who the three composers would be for the other three songs introduced in Dearly Stars—"Alive", "Precog" (プリコグ) and "Dazzling World".

[9] The four songs introduced in Dearly Stars were released by Nippon Columbia on a four-part CD series titled The Idolmaster Dream Symphony in 2009.

[24][25] A 176-page guidebook of the game titled The Idolmaster Dearly Stars Delicious Album was released on November 6, 2009 by Enterbrain.

[26] The book contains five chapters that detail the plot and characters, gameplay system, data related to in-game items and game mechanics, and interviews from the cast and development staff.

[35] Despite the technical limitations of the Nintendo DS compared to other games in the series that have been developed for the Xbox 360 and PlayStation Portable, Miyokawa described the movement of the idols during performances as "better than expected," and welcomed shots of the audience waving glow sticks.

[4] While another reviewer for 4Gamer could not deny the lower visual quality of the performances compared to previous Idolmaster games, the unexpectedly high sound quality of the songs in combination with well-done dance sequences, albeit on a small screen, was considered by this reviewer as "thoroughly enjoyable.

[3] Miyokawa suggested that Ryō may have been created to lessen any sense of awkwardness that male players would feel from playing as female idols, but upon playing his scenario, Miyokawa noted that the player is naturally able to get into the story, in part due to the comical events surrounding Ryō's story that deal with him cross-dressing.