Nothing appears from nowhere
Early on we wrote one sentence on the whiteboard and made everything obey it: every reward in the arena must come from somewhere you can point at.
What the law changes
Cut a rival captain and their crew doesn't vanish into a score popup — the conserved mass drops where they fell as a marked rival hoard. Sprint and the size you burn (the cost is on the button: 2.0× speed for −4 size per second) scatters behind you as wake loot in your colour, collectable by anyone, including the captain chasing you. Even the arena's chests are placed spend: a big reward you can see and weigh before you commit to the approach.
Why bother — most games don't
Because conservation is what makes a lead feel dangerous instead of safe. In a game where killed mass evaporates, the biggest worm is just a number other players can't touch. In a conserved arena, a giant is a walking treasury with an exposed head — worth hunting, worth vulturing, worth baiting. Every advantage stays physically present in the world and therefore takeable. That's where the genre's drama actually lives.
The subtle consequence: information
Conservation accidentally built our information system. A pile of hoard means a fight just ended here and the winner is nearby. A trail of wake loot names who paid for it, where they went, and how desperate they were. The arena floor becomes a readable record of the last sixty seconds. We didn't design that; the law produced it, and now the best players read the floor like a newspaper.