A huge meteor struck and destroyed all life on the planet with exception of a few humans who survived in a bunker. They won't last long as things are now and what's worse, that meteor was just the first of many that are on the way. You must keep the tectonic, atmospheric, biological, and climate systems all within the realm of a humans ability to survive it. There are no cards to pull, no magic to use. There are no power points to collect. As Soter, you have full control over the yourself (the planet) at all times. Avoid an ice age or global warming by balancing the pollution levels. Feed the people by creating fish. Keep the plant growth in check by crabs and turtles and cleanse the ocean with clams and starfish. Or maybe evolve some creatures onto land, and promote the growth of trees. Do everything you can to grow the population.