Every round you collect five sparks, and every move you make is remembered. Next round, the person who made those moves is back, running them again, and touching any version of who you were ends everything. The arena never adds a single enemy. It just keeps adding you.
Why it exists
Most arenas get harder by adding enemies. This one never adds a single stranger. It records you, thirty times a second, and next round the person who made those moves is back on the floor running them again. Touch any version of who you were and the run ends. Round five is you against four of yourself, and every one of them is doing something you once thought was a good idea.
Your ghosts are exact
A ghost is your own recorded path replayed to the pixel, at the same round time you made it. Nothing is smoothed and nothing is invented, so when a ghost cuts across the spark you were heading for, that was you, cutting there, one round ago.
Finished ghosts stay
When a ghost runs out of recording it stands where it stopped, still lethal, still you. The arena fills with the places you paused as well as the paths you took, and the safe ground shrinks round by round until there is nowhere you have not already been.
The kill-cam says it plainly
You ran into who you were, and it names which round. Your best is the number of rounds you outran yourself, and the toy keeps it for next time.
The quiet parts
No account, no ads, nothing leaves your browser; your ghosts dissolve the moment the run ends. Nothing in this room measures, diagnoses, or knows anything about you; it is a toy about how minds wobble, made with affection for the wobble.