Flag[5] is chosen in range 1..100 upon starting a new run. It is afterwards written to the 'fun' variable in the undertale.ini file.

Requirements Results
  • Flag[5]: 65
  • Fun: 65
  • Flag[7]: 0 (the final fight must not have been completed)
  • plot: greater than 100 (defeated Papyrus)
  • Chance: .5
 room_tundra3A (47) will send to room_soundtest (270). Fun and flag[5] will be set to 0.
  • Flag[5]: 56-57
  • Fun: 56-57
 The crossword puzzle in room_tundra9 (55) will be in "nightmare mode".
  • Flag[5]: 66
  • Fun: 66
 When moving to the room right of room_water_savepoint1 (94), you will end up in room_water_fakehallway (268). Fun and flag[5] will be set to 0. The room has a .1 chance of spawning the grey door to room_mysteryman (271).
  • Flag[5]: greater than or equal to 80 and less than or equal to 89
  • murderlv: less than 8 (did not progress a Genocide route past Papyrus)
 The NPC "clamgirl" will appear in room_water_friendlyhub (116). On v1.09 (Nintendo Switch) and later, if flag[7] is 1 (completed the True Pacifist final fight), and flag[279] is 1 (talked to Clam Girl before said boss), and flag[5] is exactly 81, triggers additional "gcon" dialogue and sets flag[5] to 0.
  • Flag[5]: 61
  • Fun: 61
  • Flag[7]: 0 (the final fight must not have been completed)
  • Chance: .2
 The NPC "gaster_follower_a" will appear in room_fire_elevator_r1 (156). Fun and flag[5] will be set to 0.
  • Flag[5]: 62
  • Fun: 62
  • Flag[7]: 0 (the final fight must not have been completed)
  • Chance: .5
  • murderlv: less than 12 (did not progress a Genocide Route past Undyne)
 The NPC "gaster_follower_b" will appear in room_fire_elevator_l3 (169). Fun and flag[5] will be set to 0.
  • Flag[5]: 63
  • Fun: 63
  • Flag[7]: 0 (the final fight must not have been completed)
  • Chance: .5
  • murderlv: less than 12 (did not progress a Genocide Route past Undyne)
 The NPC "gaster_follower_c" will appear in room_fire_elevator_l2 (168). Fun and flag[5] will be set to 0.
  • Flag[5]: greater than or equal to 90
  • Fun: greater than or equal to 90
  • Flag[7]: 0 (the final fight must not have been completed)
  • plot: greater than or equal to 110 (survived Undyne's first attack)
 The NPC "mkid_goner" will appear in room_water7 (91). Access it from room_water8 (92). If talked to while holding an umbrella, flag[5] will be set to 0 but the change won't be committed until you save.
  • Flag[5]: in range 40..50
  • Flag[7]: 0 (the final fight must not have been completed)
  • Flag[277]: 0 (the call must not have occurred before)
  • plot: less than 120
 In range 40..45 the sans refrigerator phone call will occur. In range 46..50 the pizza phone call will occur.
  • Flag[5]: in range 2..39
  • Flag[7]: 0 (the final fight must not have been completed)
  • Flag[277]: 0 (the call must not have occurred before)
  • plot: less than 120 (must not have reached Undyne's boss battle)
 The wrong number song phone call will occur in room_tundra_dock (70).