I don't understand, if it is saying that it is not a virus then the detection must have been corrected ?
Or it wouldn't have been sent to the virus chest to start with.
Then there must be something else going on, which we would need more information. Use the 'Restore' option in the virus chest to send a copy of the file back, (a copy remains in the chest)). Now try starting the game again and if avast alerts again, can you capture a screenshot of the avast alert window and attach it in your reply.
Some games use anti-cheat functions and these are generally hidden so they can't be circumvented, this can at times look suspicious, as some malware does the same. That is why a screenshot of the alert will help.