This is not a game but a musical toy.
You can make music by placing blocks.

Updates
v.1.1.1:

Added cart label image

v.1.1:

Refined the block selector
Added: glitch noise
Added: twinkling signals
Fixed: Beepers won't get hit in some cases

Controls
arrow keys: move cursor
z: place a block remove a block
x: switch to block selector
<block selector>
left or right : change block
zx: switch to circuit editing
Blocks
Signal Generators (rightdownleftuprotating): generate signals periodically.

Beeper: plays a little sound when get a signal.

Hints

The pitch of a beeper's sound changes depending on its x-coordinate and color of a signal.
You can make a diagonally moving signal by making collide two signals.

Older Versions
1.1