It is r/place with an opponent. A 256x256 canvas, 30 charges that refill one every 30 seconds, and an adversary called La Maquina who spends the whole day putting out the lights people leave on. She lays sieges on the works people build, declares blackouts on a quadrant before she carries them out, and comments on what she is doing while she does it.
Two things that make her feel less like weather and more like an opponent. Raising a tower makes it harder to kill: she has to take it down one storey at a time, and while she does you can build it back up. And what she takes she builds with, raising her own cold cubes out of the dark next to yours. They come down in a single pixel if you reclaim the cell.
No account, no ads, no download. It runs in the browser and you can paint your first pixel about five seconds after opening it: ultimaluz.com/r/lemmy-gaming
Fair warning: she erases. What you see on the canvas is what people have managed to keep.
I am the developer, happy to answer anything.