The world is in danger from invading aliens. Only our spacemen can save the planet, except they have been trapped inside asteroids. Release exactly the number of spacemen needed in order to fight off the aliens.
The aliens have made it tricky. Solve the riddle under the alien spacecraft and select that total from the numbers on the asteroids. You can select more than one asteroid to add up to the total. For example, if the riddle is 1 + 2, you can select 3, or you can select 2 and 1, or you can select 1 and 1 and 1.
The faster you solve the problem and release our spacemen the faster they can save the world, and the more stars you will receive. You can challenge yourself by selecting a higher difficulty level and earn the title Captain or Admiral. Good luck Cadet. We are counting on you.