Is life a video game? Well, taken literally, this is a fairly narrow question. A "video game" is a program created for entertainment reasons, with some degree of real-time interaction with a human player, running on an electronic computer (and of course, I assume that we're all savvy enough here to understand that game "consoles" - whether at home or in an arcade - are just special-purpose computers.)
Taken literally, I'd have to say no. However, I think you mean something a bit broader: Is our world artificial, a simulation created for some unknown purpose (perhaps entertainment, perhaps not) by parties unknown?
If the answer is 'yes', then what is our place in this simulation? Are we the 'players' or merely the characters? Is it like "The Matrix", in which we all HAVE an actual, external, physical reality, separate from the simulation? Or is it like "The Thirteenth Floor", in which the great majority of the human characters are ALSO mere simulations? Could it even be like "Dark City" in which we actually are just what we believe we are - flesh and blood people - living in an artificial world, produced specifically to deceive us, by parties unknown?
If our world IS a simulation, then what precisely is it a simulation OF? Is the greater world outside the simulation anything like our simulated world? Or is it very, very different? It could be so profoundly different that we could never understand it. The minds that created our world may view us as a weird mathematical abstraction, with no real-life analogue.
Perhaps a better question; could we ever KNOW if our world is a simulation? And even if we can - does it matter? In "Dark City" and "The Thirteenth Floor" the hero discovers flaws in the simulation, and infers the existence of the greater reality. Yet in both these films, the beings who created the simulation (aliens in the case of 'Dark City', humans from the future in 'The Thirteenth Floor') were really, relatively speaking, only a LITTLE more advanced than the captives within the simulation. What if, instead, the beings that created our simulation were god-like, their power and wisdom dwarfing ours the way ours dwarfs an amoeba's? Then the possibility of our finding a chink in their simulation is virtually nil. At which point the question becomes moot; we may live inside a very elaborate simulation, but our experience of it will always be indistinguishable from the real McCoy.
There would actually be only trivial differences between this scenario and many religious accounts of creation.