I'm some sort of purple, googly-eyed jellyfish, and the world around me is a blocky maze. I'm using the WASD keys to steer my character and using the mouse to aim and shoot at an array of colourful, bouncing, shooting fishblobs . I am collecting the power-ups. I understand this.

I do not understand this. I'm picking up power-ups, but they aren't doing anything. Why aren't they doing anything?

Inside A Star-filled Sky is made by Jason Rohrer, the creator of Passage and Sleep Is Death. It's an infinite, recursive shooter. Like when you play rounds of Counter-Strike for a really long time? No. Let me tell you what like.

At the top centre of the screen is a list of the three power-ups I currently possess. Right now it's increases to health, bullet speed and bullet size. In the top left of the screen is a list of the three power-ups held by the creature I'm currently inside. Those start as the same three power-ups I currently hold, until I pick up a bullet spray power-up, which replaces the health increase. But the character I'm controlling doesn't change until I find the level exit and head upwards. The screen blurs and pulls out, giant pixels filling the screen and then shrinking down until they're the same, small size of my previous character. I look completely different now. Now I'm a green, googly-eyed bloctopus.

I look different because I'm now controlling the creature I was previously inside. The me I was previously inside. As a consequence of the power-ups I collected and replaced, the new me has less health than on the last level, but has the three-bullet spread given by the bullet spray power-up. I have become the changes I made inside of myself.

Jason Rohrer got a lot of attention for simple, metaphorical games like Passage and Gravitation . Those were fine, but his last game, Sleep Is Death, was far more interesting.

In Sleep is Death , one player controlled the main character in a story, while a second player directed the world around them. It was a mixture of adventure gaming and pen-and-paper, cooperative storytelling, and it was remarkable. Inside A Star Filled Sky is remarkable, too.

I don't like the changes I've made inside myself. I shift-click on my new character and go back inside, pick up some different power-ups - a heart again, seeking bullet, a bouncing bullet - and then pop back through the same exit to become them. My appearance hasn't change since I was last on this level, just my powers. I understand this!

I don't understand this. I start exploring the level, and come across a large room filled with enemies. The music becomes more complex, generating its beats from the movements and bullets on screen. I dodge around the enemies, find a corridor and slip down it.

I come across an enemy, a one-eyed squigglefish spewing fast, giant, sprays of bullets. The corridor's too thin to avoid it, and there's no way I can kill it with my current load-out, but I don't want to change myself yet. I shift-click on the enemy and head inside it .

Hey, squigglefish! I'm inside your body, ruining your dude. I pick up some power-ups - the worst, lamest power-ups I can find. I locate the exit and pop back up to my former level. The fierce, venomous squigglefish is now sad, firing one, lonely bullet forward. I pop him easily and move past.

You can go inside enemies! I understand this.

I go inside the next enemy I find. Silly blobby enemies. Wait, can I—

I go inside the next enemy I find - again. I'm inside an enemy inside an enemy. I understand this! This is great.

I head inside another enemy. I keep going. I am inside an enemy inside an enemy inside an enemy inside an enemy inside a power-up.

Inside a power-up? Damn.

I don't understand this.

After an initial fixed price, Sleep Is Death switched to a “name your donation” payment model. It was successful enough that Inside A Star Filled Sky is going to start that way when it's released later this month. There will be a minimum cost of $1.75 to cover bandwidth and credit card fees, but you can pay whatever you think it's worth above that.

While inside a power-up, you can pick up more power-ups. Just like with enemies, when you shift back up and out, the power-up has taken on the properties of those you collected inside. Enter a power-up that boosts bullet speed and collect three health power-ups, and the power-up on the level above changes to become a 3x health boost.

I enter a power-up within a power-up and discover more powerful power-ups, and consequently every enemy here is a raging, spewing, speeding, bouncing, chasing globulous, wiggle-eyed slushball. It is terrifying, but by travelling inside these enemies and changing them, I could render them all inert. I don't. I die, I get sent back down a level, I try again and head back up.

I understand this. I am inside a power-up inside a power-up inside an enemy inside a power-up inside myself inside an infinite number of selves I haven't become yet. Inside A Star Filled Sky is extremely clever, and rife with metaphor. I die, I get sent back down, try again and head back up.

I understand this. I am one upward exit away from having a fantastic power-up combo made from level four health, bullet size and bullet speed increases. This will be amazing. I will be unstoppable. Inside A Star Filled Sky is a pretty dreadful name. I die, get sent back down, head back up.

I understand this. Inside A Star Filled Sky is bigger than the known universe, and though goalless, it pushes you to continue just to find out how much better you can make the next you, where “better” means giant, bouncing bullets spewing from all sides of you and popping anyone you meet.

I understand this now!

It is like when you play rounds of Counter-Strike for a really long time.