2 Common+ or 8 Very Rare+
Gravitar was an Atari 2600 game. You pilot a spaceship with controls similar to Asteroids, but with the addition of a very strong point of gravity on each of the game screens. You have to avoid being sucked into the center of gravity while shooting down all of the spaceships and missile turrets on each level.
From the instruction manual:
The evil Gravitar has set out to destroy the universe. His deadly weapon?
Gravitar bombards unsuspecting galaxies with his hostile gravitational
forces. He then installs a powerful reactor within each solar system of the
defeated galaxy, creating a killer sun that destroys all life on the
surrounding planets. He blockades those planets with lethal rammers and
with automated bunkers programmed to shoot.
So far, Gravitar has conquered four galaxies, each made up of three solar
systems. And intelligence reports hint that our galaxy may be next. Gravitar
must be stopped before he adds our galaxy to his list!
This game is worth anywhere between $2 and $200 USD, (depending on the cartridge label). Games with boxes and manuals are worth more.