Death by Cube is a fast-paced twin-stick shooter where the player controls the amnesiac robot LEO. The only thing he remembers is he has to rescue his love SELSIE and in order to do that he needs to travel through seven worlds. Shown from a top-down perspective, those worlds consists of small, slickly designed rooms where hordes of enemy robots are unleashed. LEO has a basic laser weapon that can be upgraded with different firing patterns and homing bullets. To complete a level wave after wave needs to be survived. Based on the performance, chips are awarded needed to unlock new levels and upgrades (suits) that improve his abilities. To unlock everything levels need to be replayed multiple times to gain more chips.
Next to the firing there are two moves that are vital for survival. The first is dash that can be executed for a short while. Surrounding enemies will temporarily be stunned in confusion and lower their defences, which makes it easier to take them down. The second is a shield that catches all incoming bullets and then fires them in a chosen direction when the shield is lowered again. It cannot be held for an infinite amount of time or the bullets explode. Additional power-ups, such as a giant laser, are provided in-game after performing combos. Others are a spread shot, a reverse shot and a homing shot. It is also possible to create decoys that lure away enemies for a short time.
Online multiplayer is supported for up to eight people, in two teams. There is pure death match as well as team-based battles around bases.