A spaceship nips back and forth across the bottom of the screen while aliens line up like the damned at the top, void-plodding from side to side, their ranks regimented, their only purpose to painstakingly work their way left, down, right, down, left, down. It’s one of the first things that ever happened anywhere and shortly after the aliens moved to a burb called Galaxian and learned how to break formation and dive. A dark day for tiny ships that do not understand how to move vertically themselves. Debug Formulation is an indie game that harks back to those early days but complicates things just a little, while looking and sounding rather spiffy.

Whenever I play something like this I always try to work out whether it’s better to hold down the fire button or place my shots carefully. Debug Formulation seems to know that is the extent of my thinking so it ensures that neither method is correct, but rather a combination of the two.

The ship fires a cannon but while a shot is in motion it cannot fire again. Except it can. Sort of. There’s a secondary fire, tied to the same button, which only destroys objects at close range. That’ll be either swooping aliens or the cores that drop out of them and those cores are the second complication.

Exploding an alien isn’t enough to get rid of the pest, you also have to burst the core that is left behind, which will then release a powerup. If the core falls off the bottom of the screen – and brilliantly, bullets will juggle them back up again even before destroying them – the alien respawns. Each wave of enemies is tougher, with more aggressive nasties to fight and more missiles flying around the place.

I probably wouldn’t be writing about this little demo though if it wasn’t such a pleasant aesthetic experience. The music, which is procedurally generated, reminds me of sea mammals cooing to each other on a moonlit night, while the particle effects and gentle glow of destructive projectiles are quite lovely. While it can become hectic, I reckon it’s a strangely relaxing experience. You can download the demo here.