Lattice is a high-speed abstract rail-shooter. The player constantly moves forward at a rapid pace along straight square pathways connected by junctions. Enemies and obstacles swarm from all sides, attacking or obstructing the player, which must either shoot and destroy them or avoid them by either moving to other sides of the path or jumping over them. The player can change their path through the stage at various junctions, as well as turn around and head the opposite direction if necessary.
The goal of each stage is to locate and capture three "key capsules" within the time limit and without running out of life. As the stages progress, they become increasingly complex, introducing more branching paths and ways to traverse the paths such as the ability to jump to adjacent pathways. There are also a variety of special weapons that can be found.
At the end of each stage, the player is graded on several criteria and given a score. Progress is saved using passwords. There are three difficulty levels, and seven stages in total.