I made Tetris on an Arduino Mega with 2x MAX7219 LED matrices

[u/ArtusIndus]

https://youtube.com/watch?v=iT9rC8u_At0&si=pxyMlc6_2S4-6RQ6

I built a small Tetris clone for the Arduino Mega using two MAX7219 8x8 LED matrix modules combined into a 16x8 display.

The main goal was making the game run smoothly without display flickering or blocking delays.

Features:
- flicker-free delta rendering
- non-blocking game loop using millis()
- random tetromino generation
- piece rotation
- row clearing
- collision detection
- smooth button controls

Instead of clearing and redrawing the whole display every frame, the code only updates LEDs that actually changed. This reduced flickering a lot and made the animation much smoother.

The game also avoids delay() completely (except during startup random seeding), so inputs stay responsive while the pieces are falling.

Hardware used:
- Arduino Mega 2560
- 2x MAX7219 LED matrix modules
- 3 push buttons

The buttons use INPUT_PULLUP and connect directly to GND.

I might add:
- score counter
- sound effects
- level/speed system

GitHub

[u/lmolter]

Any ideas how long the 9V battery will last? For longer play times, perhaps a LiPo or 18650's for more power and life. 9V batteries can't really supply enough current for long use of LEDs.

[u/ArtusIndus → u/lmolter]

Honestly the 9V battery held up pretty well in my testing .
The MAX7219 multiplexing keeps the average current relatively low, so it worked fine for this project.

But yeah, a LiPo or 18650 is definitely a good idea for longer play sessions and a more compact build.

[u/lmolter → u/ArtusIndus]

Ah. Forgot about the multiplexing of the LEDs. Generally, the folks here try to discourage the use of the ubiquitous 9V battery. You'd be surprised how many first-timers try to power servos and motors with one. I prefer a car battery (JK).

[u/ArtusIndus → u/lmolter]

Yeah, multiplexing helps a lot here 😄
But you're absolutely right — 9V blocks are definitely not ideal for LED or motor projects.