Mario & Luigi: Partners in Time, developed by AlphaDream and published by Nintendo, launched in 2005 for the Nintendo DS — arriving in the console's first full year on the market, when developers were still discovering how best to exploit its dual screens and dual-processor architecture. It served as the direct follow-up to Mario & Luigi: Superstar Saga (2003, Game Boy Advance), inheriting that game's comedic tone, action-RPG battle system, and the brotherly banter between Mario and Luigi while dramatically expanding the scope by introducing baby versions of both heroes. The Nintendo DS's dual screens proved a natural fit: the top screen typically displayed the overworld or enemy information during combat, while the bottom touch screen handled menus and, in certain sequences, the baby brothers' actions, though the game primarily relied on the face buttons rather than the stylus.
The central conceit of Partners in Time is time travel. Princess Peach departs in a time machine to the past, only to become entangled with an alien invasion by a race called the Shroobs, who have conquered the Mushroom Kingdom of that era. Adult Mario and Luigi follow her through time holes and team up with their infant selves, creating a four-character party that is the mechanical heart of the game. In battle, each pair — adult brothers and baby brothers — is mapped to a dedicated set of buttons: A and B control Mario and Luigi respectively, while X and Y control Baby Mario and Baby Luigi. Players must press the correct button at precisely the right moment to execute attacks, dodge incoming strikes, or trigger counterattacks, demanding genuine attention and reflexes rather than passive menu navigation. Bros. Attacks, the game's flashiest offensive options, require coordinated multi-button inputs across all four characters and consume Bros. Points, functioning as a limited but powerful resource.
Outside of battle, the four brothers navigate interconnected overworld areas spread across both the present and past Mushroom Kingdom. Baby characters can be carried on the adults' backs, and many environmental puzzles require switching between formations — babies thrown to reach high ledges, adults stomping switches that babies cannot reach. This layered traversal design gave the DS version a sense of physicality that distinguished it from a straightforward port of the GBA predecessor's ideas. The game features a hub in Peach's Castle from which time holes branch out to distinct themed regions, each culminating in a boss encounter against a Shroob commander.
At launch in late 2005, Partners in Time was received as a polished, content-rich RPG that made strong use of the DS hardware without resorting to gimmickry. Critics praised the writing's humor, the inventive boss designs, and the satisfying rhythm of the battle system. Some noted that the four-button combat, while clever, occasionally became hectic during multi-phase boss fights, and a handful of reviewers felt the game's pacing in its middle chapters was slower than Superstar Saga's. Nevertheless, it established AlphaDream's RPG series as a genuine DS staple and set the template for the subsequent Mario & Luigi entries on the platform.
