[Rufus]

Since no one posted an update to this yet :p.

This works by checking the opcode of a game class that is null unless you are inside a game.

Warcraft_CheckGameState proc
;//Game state checking function

.data
    FXN_GameClass dd 6FAA1988h

.code

    ;//Move GameClass into EAX
    mov eax, FXN_GameClass

    ;//Check to see if we're in a game and return true/false.
    .if byte ptr [eax] == 0h
        mov eax, 0
    .else
        mov eax, 1
    .endif
    ret

Warcraft_CheckGameState endp