Sinking

Deep Sea Adventure.  

A pocket-sized push-your-luck game where you are treasure-hunting divers who, for reasons of economy, are sharing one oxygen line.  Carrying treasure not only uses up oxygen, but slows your movement.

After 3 dives, you count up how much treasure you've managed to get back to the sub.

After 2, no-one had managed anything.  When the oxygen runs out, all the treasure gets dropped to the bottom of the sea, but doing so shortens the route, so it's tempting to try and get it.

Trickier than you first think.