Shelf
On the platform
Test canisters
Nudge the ballast, watch the gauge, and open each bulkhead: up is positive, down is negative.
You have opened the surface hatch before.
No timer, no score. Space or Enter also starts.
Nothing is running. The room waits exactly as you left it.
Up is positive and down is negative, so lifting things raise the gauge, waterline and pod, and sinking things lower all three.
Example: pull the lever down once and everything drops 5, so 0 + (-5) = -5.