City Blocks is a "match-3" game in which a player's main goal is to upgrade existing buildings and create new ones to make the city large enough to hold as many people as possible. Block space is at a premium, which means they lose the game if they run out of space to grow their city.
Players don't need to worry about complex game play. As with any match-3 game, they progress by matching in-game elements. In this case, they match and merge together three of the same type of building to create a newer, larger building able to contain more people. Players can also earn special buying power called "Jokers" to purchase a building of their choice to replace one that doesn't match.
The player is provided with buildings throughout the game. To move one of them onto the cityscape, they roll their cursor over the area and tap any of the empty blocks. They then continue in this fashion until they've aligned three of the same buildings. The buildings are ranked based on the number of people they can hold. Basic designs hold less than 10 people. Complex designs can hold hundreds. The player isn't restricted to straight row match-3 alignments. They can also align three buildings in a corner or L-shaped distribution.
As the game progresses, the system tracks the number of people the player has housed and keeps score. At the end, it adds the player's rank to a leaderboard. After each attempt, the game saves and displays the current city population size and sets off fireworks. The player improves their score and moves up the ranks every time they build new cities in new games.