Plasma Drift

You are one glowing cell in a petri dish. Absorb anything smaller than you, stay away from anything bigger, and see how long you last. It is agar.io in a single file, with no download, no account and no loading screen.

How to play

Move the mouse and your cell drifts toward the cursor. Distance is the throttle: the further the cursor sits from your cell, the harder you accelerate, so resting the cursor on top of yourself is the brake. Dragging a finger does the same thing on a phone.

Space is the surge. It gives you close to double speed for about a second and a half, then takes roughly five seconds to come back, and it burns biomass the whole time it runs. It also refuses to fire once you are small enough, so the moment you most want an escape can be the moment you do not have one.

Your score is your biomass, shown top left. Your best is kept in your own browser and nowhere else.

Why it exists

This was the first game I put on the site, in July 2026. I wanted something a visitor could understand in about four seconds without reading anything, and the growing-blob idea is the most readable one in browser games. There is no tutorial because there is nothing to teach. You are either bigger or smaller than the thing in front of you, and that is the whole game.

The rules doing the real work

Left alone, a game like this is just a number going up. Four rules stop that.

• Absorbing is lossy. You keep a bit over four fifths of whatever you swallow. Hunting a rival is never a clean trade, which keeps quietly farming the motes competitive with going after other cells.
• A graze does nothing. You have to be clearly larger and your body has to nearly cover theirs. Touching edges is not eating, in either direction, which is what lets you thread past something that could kill you.
• Size costs speed, but only up to a point. You slow down as you grow, then the slowdown stops, so a large cell is sluggish rather than helpless.
• You shrink constantly. A slow decay runs the entire time, so hiding in a corner is not a strategy. Doing nothing is losing, just slowly.

The camera pulls back as you grow, which is a reward and a punishment at once. You see more of the dish, and everything you have to avoid gets smaller on screen.

What the other cells are actually doing

There is no pathfinding and no coordination. Each rival looks at what is near it and picks one of four things, in this order: run from anything close and clearly bigger, chase anything close and clearly smaller, otherwise head for the nearest mote, otherwise wander, changing direction every couple of seconds. That is all of it, and it is enough to read as a dish full of things with their own agendas.

When one dies it is replaced immediately by a fresh cell at a random size, so the population never thins out and the dish does not get easier the longer you survive. The standings panel on the right is real rather than decoration: it sorts everything currently alive by mass and shows you where you sit.

Built with nothing

Plain canvas drawing, one file. No engine, no framework, no build step, no server, nothing to install. That was the point as much as the game was: proof that a real game could live on my own site as a single page I can still open and fix months later without setting anything up first.

Honest limits: the surge is keyboard only, so on a phone you get movement and nothing else. The standings are the cells in your own dish, not other people. And the best score lives in your browser, so a different device starts you back at zero.