Suggestions:
If the gadgets don’t one-hit the speedrunner, let the hunters get a temporary gadget upgrade, where it gives them a better gadget for some time, and then it takes it away.
Add a rare powerup that lets the speedrunner teleport to somewhere different.
Add an area where the speedrunner can purchase a temporary speed upgrade in exchange for some sort of currency or a temporary debuff
Add a way to let the speedrunner KO or debuff the hunters.