I don't know if it's some norm or something, but most 64bit only games have 32 bit OS not supported or something right before sysreq.
Found some examples
AC Unity has Requires a 64-bit system on top of sysreq
MGS Ground Zeroes has 32-bit systems are not supported on top of sysreq
Topic on User talk:RaTcHeT302
Yes I know, I simply had forgotten about that.