Another example of how games are living past their traditional prime.

Left 4 Dead came out late last year and was one of Xbox 360’s big holiday hits, so it came as no shock that Left 4 Dead 2 was announced for release later this year.

What is surprising is the fact that Valve, the game s developer, has just announced an expansion pack for the original game just ahead of the game’s sequel.

The pack, which will be free to PC owners and cost $7 for Xbox 360 players, adds an additional chapter to the zombie-filled adventure.

Take note because, whereas a game’s lifespan would traditionally end shortly after its retail launch, games like Left 4 Dead show increased value as a marketing tool to bolster a brand and even promote and lead into an upcoming sequel, as is the case here.