Bit. Trip Beat is a unique combination of Pong and a rhythm game. The game is played by holding the Wii-remote sideways and tilting it away or towards the body. This in turn moves a paddle on the left side of the screen vertically up or down. The objective of the game is to hit the various "balls" with the paddle coming into the screen from the right. The balls are synchronized with the beat of the game's chiptune soundtrack, creating a logical connection between what players are seeing and what they are hearing.

The screen contains two bars. Hitting a ball will fill up the top bar until it is full. This increases the multiplier and makes the visual effects in the background more complex, thus increasing the difficulty. The lower bar is emptied if the player misses a ball. If the bottom bar is depleted, the game switches into a black and white mode, similar to the original Pong game, where only the Wii-remote's speaker is active. In this mode, the player has to fill the top bar again to return to normal play. If the bottom bar runs out again, the game is over.

Bit. Trip Beat has a variety of balls the player has to repel. They are colour-coded to indicate their movement type: orange balls bounce off the paddle multiple times, while yellow balls only travel in a straight line for example. Occasionally, bonus items can be picked up with the paddle, which for example change the paddle's size similar to the power-ups found in Breakout.

At the end of each level, a boss fight awaits the player. Defeating the boss grants access to the next level, of which there are a total of three. After playing through a level once, it can be selected at the main menu.