W32/OnLineGames.ACVR is a Trojan that will infect Windows systems.

The Trojan may be dropped by other malware or may be downloaded from remote website by other malware. It may also be downloaded unknowingly by a user while visiting malicious Website.

Upon execution, the Trojan drops the following files:

kavo.exe , kavo1.dll in the Windows System folder
zz[1].exe in the Temporary Internet Files folder
mpsu8b.dll, nod2.tmp in the Documents and Settings\User\Local Settings\Temp folder
It also drops x.bat, autorun.inf, phk1f.cmd in the Root of Windows Installed Drive

More information can be found at this Proland Software page.