Holds the current game mode (0-4). Checked by the routines at 29952 (using the event entry at 24544), 31126, 31414 and 61568, and updated by the routine at 63662.

Mode	Meaning
0	Demo mode
1	The game has just started
2	Sam has entered no. 15 with the key
3	Sam has had the phone call about the key to no. 74 and gone to the top of the apartment building
4	The mob is after Sam