Picross 3D is a logic puzzle game and the sequel to Picross DS. The game features four profiles for multiple players and, excluding DLC and user-generated puzzles, 369 puzzles are available total. Scoring is based on both number of errors made and time taken to complete the puzzle. The stars earned for completing a puzzle well go toward unlocking higher level puzzles. Occasionally other challenges are thrown into the mix, including needing to complete a puzzle with no errors and needing to eliminate a certain number of blocks to grant yourself more time. A customizable "random puzzle" mode is also available upon completing a certain amount of puzzles. There is also a mode that allows players to create their own puzzles using a simple interface, similar to playing the game normally but in reverse (adding on blocks instead of breaking them away). These user-generated puzzles can then be sent to other players locally or submitted to monthly online contests.
Every stage of Picross 3D begins with a three-dimensional cube that, when solved correctly, depicts a unique image of some sort. To reach that point, the player must decide which bricks should be saved in every row and column, as well as which ones should be chiseled off. This is done by interpreting the numbers that are written on the sides of each block, with a given number indicating how many blocks in a given row or column should be preserved. (A zero indicates that the entire row/column can be safely cleared off.) However, special markers that are included with each number further indicate the ways in which the numbers of blocks in that row or column are distributed. A number with no special symbol around it, for instance, indicates that all of the blocks that are to be preserved have to be adjacent to each other. A circle around a number, meanwhile, indicates that the blocks are split off into two groups, while a square means that the blocks are siphoned off into three or more groups. Using just this basic knowledge, as well as some contextualized critical thinking based on the shape the puzzle takes as blocks fall off, every puzzle in Picross 3D can be solved.
In addition to the numbers on the blocks, the player has a few tools at their disposal to help better, more efficiently examine blocks. A chisel can be used to delete bricks that the player knows aren't part of the actual solution, while a paintbrush can paint blocks that the player wants to preserve. (Blocks that are painted cannot be broken without re-using the paintbrush tool again to revert them back to a breakable state.) If a player breaks a block that's actually part of the solution, the game will preserve it while counting as a strike, with too many strikes resulting in failure. In order to complete a puzzle, the player must chisel away all of the unnecessary blocks, but it is not otherwise required to paint the remaining ones that need to remain. The camera can also be rotated so as to examine each puzzle from any given angle and the player is also able to use sliders on two axes that temporarily remove blocks from view so that pieces that embedded in interior layers can be directly examined.
On most stages, players can receive up to 3 stars: 1 star for finishing the puzzle, 1 star for finishing under the time limit, and 1 star for not making any mistakes. Each group of puzzles generally has a Silver and Gold puzzle at the end that can be unlocked with a certain amount of stars, typically requiring most puzzles to be finished with 2 or 3 stars. These optional puzzles are typically the hardest ones of the group.
In addition to the standard puzzles, there are also a few variants to the standard game. Time challenges force you to beat the puzzle within a certain time limit, with further progress adding 30 seconds to the challenge timer. Construction puzzles are a group of smaller puzzles that combine at the end to form a larger item at the end.
Picross 3D features fairly standard DS multiplayer functions. Players can send and receive user-made puzzles locally, as well as send a trial version of the game to others.
Picross 3D features post-release downloadable support seen in few other DS games. Packs of new puzzles have been put out weekly since the game's early 2009 release in Japan. All of the puzzles are attributed to "Nintendo," with the exception of a monthly release where users have spent the last month submitting puzzles on a certain theme. The selected puzzles are released in five packs, all at once.