A land-grab played on a sheet of steel, where the rust is you. Claimed ground cleans itself back at the edges, so sitting on a lead loses it. And the line you draw stays wet, drying slower the longer you make it, so a greedy loop is dangerous the whole way round rather than only at the end.
You are a spot of rust on a steel plate, and the plate is being shared with three others. Everything you have claimed is quietly flaking back to bare metal, so the only way to hold a lead is to keep taking more.
Step off your own territory and you start drawing. That line is wet paint until it dries, and touching a wet stretch - yours or anyone else's - breaks you apart. Get back to your own ground and the loop closes, filling in everything it encircled.
The catch is that the line dries more slowly the longer you make it. A short dash is dry almost before you have finished it. A long greedy sweep is still wet at the far end when you come back round, so the big claim is not risky at the moment you close it - it is risky for the entire journey.
Territory flakes away at its edges, a little at a time, and it never stops. A tidy square left alone will be gone in a couple of minutes, so there is no safe position to defend and nothing to be gained by waiting.
That is deliberate. Without it the correct play would be one careful loop followed by an hour of standing still. With it, the question is always how much you can take before the wet end of your own line catches up with you.
Rivals draw wet lines too, and theirs kill you exactly as yours do. Cutting across a rival mid-loop is the fastest way to take a large piece of the plate, because everything they had enclosed goes back to bare steel.
They come back somewhere else a moment later, so the plate never goes quiet and a lead never lasts long enough to relax into.