Available in version 46 and later. (for new IRPL commands)
GetGameTickCount
Pushes the game's tick count to the stack. The tick count is similar to the game update count, except it always increments even when the game is paused. It only ever goes up through a mission. Ideally, it increases at 30 fps.
Also refer to GetGameUpdateCount for additional timer-based commands.
trace(GetGameTickCount)