Elements.

 The elements are essential in daily life. Think of ice, water, fire, wind, earth, light, and darkness. These elements make up our life as a whole. You can't live without at least seeing all of them. 

Elements in games are very personified. The characters sometimes harness them to cast spells or use attacks. In some games, the elements are their own beings, each having a seperate personality. They're essential in games as well, because without them, getting through would be practically impossible.

For example, in Tales of Symphonia, an RPG for the Nintendo Gamecube, the elemential beings are used to unite two worlds that were split apart. They're essential in the plot, and are used to bring the main characters closer together. They have to fight for the elementials, and by fighting together they make pacts with them.

The more you look at these games, the more you see the connections to nature and the elements. From Final Fantasy to Resident Evil (that's a stretch there, haha), you can always find elements where ever you go.