Set 0x725B24 in data.win to 1. List of features:

Trigger Result
By default All "fun" events will occur regardless of other parameters
Page up Increase "steps" by 100
Page down Make attack equals to 999
5 Increase battle group
Ins Next room
Del Previous room
S Save
L Load
0..4 Choose save file
F + 6 Go to room_fire2 (138)
W + 6 Go to room_water1 (82)
T + 6 Go to room_tundra1 (44)
E + 6 Go to room_castle_front (219)
R + 6 Go to room_ruins2 (7)
Y + 6 Go to room_truelab_elevator (244)
G Box
G (in a shop) Add 5000 gold
O Take out panel
I Put away panel
M Increase murder level
P Toggle room speed between fast and slightly slower than normal
F Set room speed to fast
U Enable Undyne calls
F3 Creates file system_information_962
F7 Add 500 gold
F9 Stop sound
F10 Phase through walls
F11 Go to room_water1 (82)
F12 Restart room
V Collision boxes visible
Backspace Fast walking speed
End Based on plot, play current "monster tale" event
Home Battle current group (default is 140, change at 0x009F553C)
Delete (in battle) Set hp to 999
1 (in battle) Slow down
2 (in battle) Speed down
8 (in battle) Decrease turn timer
9 (in battle) Increase turn timer
F6 (in battle) Set mercy to 0 and attack to 999
O + P (in battle) Set mercy to 9999
During specific fights Many testing features