WarioWare D.I.Y. [Model NTR-UORJ-JPN]

Released on April 29, 2009 in Japan.

Development of WarioWare D.I.Y. began in September 2003 when series director Goro Abe decided that due to how entertaining it was for the team to create microgames, they should make a game that allowed players to do the same. In an interview, Abe referenced other video games that allow players to create their own role-playing or shooting games, but despite finding it fun he would quit making them before finishing them. Because of this, he decided that the short nature of the WarioWare series' microgames were perfect for this kind of game, allowing for those with a shorter attention span to make use of the game. Development took a long time as a result of the launch of the successor to the Game Boy Advance, the touch-controlled Nintendo DS, which Abe felt was a more ideal way to create microgames. However, due to a combination of the difficulty in creating microgames and other projects Abe had to develop at the time, the title was put on hold and development ceased for a time.

The project gained new life during the development of the Wii title WarioWare: Smooth Moves when the developers learned of the WiiConnect24 feature that allows players to exchange or send data to other players. He decided that with D.I.Y., players would be able to make microgames on the Nintendo DS and then send them to the Wii to play. Development restarted after the completion of Smooth Moves. Another designer, Masahito Hatakeyama, got involved after discussing the project with Abe. Hatakeyama was also interested in video games that allow players to make their own content, but he suffered from the same problem and would quit creating his content a third of the way through. He also cited Mario Paint as another influence for allowing him to make his own content. He eventually asked Abe if he could participate in the game's development, which Abe agreed to. Taku Sugioka, an employee of Intelligent Systems who had also worked on the DSiWare video game WarioWare: Snapped!, had heard that after Smooth Moves was completed, Abe was going to try something new. Soon after, Abe asked him if he would be interested in participating in its development. He found it to be an interesting project, but was not sure if Abe's ideas could translate well into a video game.

The drawing and music-making portions were made to be based on the drawing and music-making tools of Mario Paint. However, they found difficulty in designing the portion of the game where players designate the objectives of the microgames. Originally, they intended to make characters and items, which they designated as "objects", able to move depending on the players wishes, but they needed to make the game interactive and approachable for players. After Smooth Moves, development of D.I.Y. took two more years to complete; one of those years was spent attempting to figure out how to make such interaction and approachability doable. Eventually, they decided on splitting the microgame design process into three phases – the object phase, the background phase, and the sound phase. They created a framework on which they viewed as successful after a designer created a microgame in a few hours. The first version of the editor was far less complex than that of the final version, the approach being to start with a small number of necessary functions and only add others if necessary, rather than having an overly complex editor and removing unnecessary functions. To test its capabilities, the development team set to recreate Wario's stage in WarioWare: Touched! They were able to replicate "almost 100%", with some adjustments made to games that could not be fully recreated. During development, Abe emphasized to the other staff members that it was unnecessary to create highly complex and technical games, as they would only last a few seconds.

At this point, the development had picked up, Sugioka commenting that the team was amazed by this since he was just a designer and not a programmer, meaning he did not have access to special techniques to do this. As the development continued, the game design mechanics grew from the simple test model, as if they were adding to a puzzle, in Sugioka's words. The developers intended on keeping it simple, however, only implementing six buttons. For example, for a microgame that features a jumping character, players may dictate where the character may jump by selecting the "Boing!" button. While Hatakeyama wanted to add more functionality, Abe retorted by commenting either that the player could combine two functions to do what Hatakeyama wanted or that the microgames only lasted a few seconds and did not need to be too complex. The development team attempted to recreate microgames from WarioWare: Touched! to test how easy it would be for players to do so. For some they could recreate, while others they could not. In response, they adjusted the game to make the ones they could not recreate workable. The debugging process was a difficult part of the development due to how many possibilities there were in creating microgames.

While the game originally was going to use a normal Nintendo DS game cartridge, it uses a NAND flash memory card in order to save and load microgames faster and allow players to store more microgames. While this was initially rejected due to a tight schedule, it was eventually implemented. However, during the mass production phase of the development, the game would stop when they tried to utilize the memory. Sugioka was placed in charge of debugging the NAND card, and eventually found the cause. While Abe considered that there would be people who would not want to make microgames, he implemented a feature that would allow players to edit the microgames the developers included to make their own. Initially, they considered having players download microgames from people who have given their friend codes to them, Abe commenting that microgames made by friends and family are more entertaining than those downloaded from anonymous people. Both methods of exchanging microgames were eventually implemented in the final game.