Depends on the game. If you need five, you can go with the eastern elements - water, fire, air, wood, metal. That give you nice established elements (as fire isn't one. It's a chemical reaction. The things made of fire are: fire. Maybe fire elementals, too, if you have them in the game).
If you take a page from the Dresden files, there is the classical Eurapean 5 plus Spirit. And Spirit is sort of catch-all for "energies" - this includes stuff like invisible kinetic force, or creating light, also making something invisible (technically, you could also call that "manipulating light" but it might not be) and so on.
If you want to view the elements as building blocks of the world, you can use the four plus "life" or "blood" or "soul" (or "spirit". Also the eastern "wood" sort of maps here) - something to signify the living. If you take this approach, you would probably want to swap "fire" with "energy". Or preserve the name but change the function.
It really, really depends what you want the elements to show. You can add "void" or "darkness" (or call it "light" and let it control both) or "lightning" or "passion" (yeah..."heart") and each would shift the overall feeling in a different way. Also, it depends on whether you want derived elements or not (water -> ice, maybe temperature, weather). For example, this may determine if the final element is derived or if the current ones were derived from it. Also, another aspect of "what role do they show" is how are the elements set up - are they interconnected? For example, the classical four (or the eastern five) are equal among each other. Because each covers a different niche. So with this in mind, do you want the final one to cover something the others don't (hence "life", for example) or do you want it to be something else ("void" would be the opposite of elements, for example or just sinister stuff. Could be the opposite of life).
If you want an entirely different take on things, then let's take Mage the Awakening for example: using the five Supernal realms - Aether (sort of pure energy. The realm is vaguely heaven), Primal Wild (the flesh and soul of living beings. The name describes the realm), Arcadia (governs the fate and fortune....also time. The realm is of enchanted forests and magical creatures), Stygia (everything dead - extinguished life and just inert materials. Yeah, the realm of the dead) and Pandemonium (in a way it's about the internal perception - the thoughts, emotions and the spacial perception - space and mind. The realm reminds of hell but it could also more of purgatory). There you go - you have five completely different sources of power that are nothing lice the classical 4/5 elements.
