IGN listed Scribblenauts in a preview of Nintendo DS games in 2009, labeling it as one of their top picks for the year. They described it as "quite possibly one of the system's most ambitious designs yet. IGN readers ranked the world debut article about Scribblenauts as the eighth best Nintendo DS article of 2008 on their web site.
The game was very well-received at the 2009 E3 Convention and was considered the "sleeper hit" of the show. Scribblenauts is the first portable video game in history to win "Best of Show" awards for E3 from any major gaming media outlet. The game was named "Best Original Game" and "Best Handheld Game" by the Game Critics Awards. Scribblenauts was named the overall "Best of Show" by Gamespot, Gamespy, and IGN, in addition to other awards. 1UP.com named Scribblenauts their E3's "Most Innovative" title. X-Play gave the game its E3 "Best Original Game" and "Best Handheld Game" awards. Ars Technica considered the game as the show's "Most Pleasant Surprise". Joystiq performed a ten-word test of the game, and found only one word, "plumbob", was not yet present in the game, but were promised it would be in the final version. Part of the success at E3 was considered partially due to the inclusion of then-recent Keyboard Cat Internet meme, which led to a grassroots-type excitement about the game at the convention. Adam Sessler of G4 TV believed that Scribblenauts E3 success was from being a small but successful game from a small company in contrast to numerous other AAA-titles from other major developers and publishers that have become standard for the convention, such that the uniqueness of everything about the game made it the standout title of the show. Scribblenauts was given a much more predominate display in Warner Bros. Interactive's booth at the next major convention, the 2009 Comic-Con International.
One example of the possibilities of Scribblenauts that led to further attention to the game are given in the ESRB's attempt to describe the "cartoon violence" and "comic mischief" within the game as to grant it an "E10+" rating. The ESRB's description includes possible examples of the game's level of violence as "a club can be used to hit an animal; steak can be attached to a baby to attract lions; rockets can be lobbed at a man". In a post at NeoGAF within a thread dedicated to the game, user "Feep" relayed the experience of discovering during E3 that he was able to go back in time with a time machine to collect a dinosaur in order to defeat an army of robot zombies that could not be defeated with regular weapons. The story, as memorialized as "Post 217", has lead to 5th Cell artist Edison Yan to create a desktop wallpaper image of the story, in appreciation of the positive fan response to the game, and the terms "Post Two One Seven", "Feep", and "Neogaf" have been included as summonable objects in the game. The NeoGAF forums proceeded to expand on their praise for the game by creating a series of avatars of video game and other related characters (which will not otherwise appear in the game due to trademark issues) for their forums inspired by Yan's art design; Yan himself has drawn several more avatars in the same style for other games such as Street Fighter II and Final Fantasy VII.
Scribblenauts was found by reviewers to live up to the premise that the game was built on the ability to bring about nearly any object imagined into the game. John Walker of Eurogamer considered the game "an incredible achievement", with its word database "so utterly complete in its collection of everything ever in the universe" and its specificness on these terms. Craig Harris of IGN asserted that "the developers fully deliver on [the] promise" of allowing player to summon nearly any imagined object, and, based on the core game alone, is an "incredibly versatile Nintendo DS experience". Ben Kuchera of Ars Technica praises the game as "undeniably new and impressive" and urged players to support games that take risks with their innovation. Ray Barnholt of 1UP.com noted that while the game "isn't exactly the be-all end-all videogame" that it received prior to release, the game remains "unmissable" due to its sheer novelty value. The game's feature of forcing the player to consider different solutions when replaying levels was seen by Anthony Gallegos of Gamespy as a "really clever way to encourage replayability while subtly upping the challenge".
However, reviewers complained about the game's poor controls, to the point that the implementation "almost kills a fantastic game". Reviews specifically commented how the touch screen is used both to manipulate the objects placed in the game and to move Maxwell; this would result in inadvertently having Maxwell walk to his death or to disrupt a delicately-prepared arrangement of objects prior to being ready to move him. Craig Harris of IGN notes that while one can direct Maxwell indirectly, the character would often fail to avoid or overcome simple obstacles, similar to troop movements in real-time strategy games, such that overcoming these issues requires a significant amount of precise controls by the player. It was suggested that while it was understood why 5th Cell opted to use the touchscreen in this manner to avoid too much flipping between the stylus and face-button controls, they would have appreciated the option for customizing the controls. The decision to use the touch screen controls was described by Walker as "possibly the most wildly stupid design decision of all time", and that if the movement controls were mapped to the face buttons, the game would have been a "beautiful thing". Walker also questioned the choice to have the game's camera snap back to Maxwell as soon as the controls for it were released by the player, as it made it both difficult to set up objects that were off-screen from Maxwell, and to watch the results of certain interactions, such as fights between computer-controlled characters, that occurred off-screen. When it is possible to connect objects to other objects, reviewers found that finding the connection points to be difficult, and would often trigger Maxwell to move.
Reviewers also identified some unexpected behavior from some objects or combinations of them, leading to a inconsistency in the difficulty of the various puzzles. Ben Kuchera of Ars Technica, in calling Scribblenauts a "a frustrating, often maddening game", described that he often encounters puzzles that, after trying several solutions that should have worked by common sense, he eventually happened upon a less logical solution that worked. Walker considered the puzzles range "between uninspired and simple and frustratingly obscure and fiddly". Many critics experienced that after getting stumped on a puzzle, they would often resort to playing around in the free play mode. In particular for the action levels, reviewers found that they would be less likely to explore alternate solutions and fall into the pattern of using the same set of objects, making these levels repetitive towards the end. On the other hand, the puzzle levels were well-received; Andrew Reiner of Game Informer stated the time spent while solving the puzzle levels was when his "creative juices were joyously sapped". The presence of the "Ollars" currency system allows players to skip levels they found difficult. Kurchera also noted that with some puzzles, the game is often better played with others, including young children, as the combination of imaginative ideas will likely eventually stumble upon a solution. Barnholt described the entire game as feeling like a prototype with its odd physics and not as polished as 5th Cell's previous games, though acknowledged the overall game is still an impressive feat for the small development team.