Can kids play left for dead 2

No, Left 4 Dead 2 is rated an 18, and only 18 year olds and above can play the game.

However, Australia released a censored version, due the Australian government not having an 18 rating for games. The censored version is rated an M15+, which only 15 year olds and above can play it.

I hope this answers your question
iFirePenguinAirstrike