Make sure everyone in your party is running this app, and set the gravity to the same value.
Here's some other addresses, that were easy to find.
 camera_control <boolean> = 3020AA61
 player_disable_movement <boolean> = 30004B66
 player_camera_control <boolean> = 30004CA8
 cinematic_show_letterbox <boolean> = 3020AA60
 game_lost <boolean> = 30004B64
 controller_set_look_invert <boolean> = halo2.exe+4A89C1
if you're wondering what those numbers are, they are in order of xbox7887 or is it kornman? 's list.
"physics_constant" was labeled before the true gravity value, and the only changes took place in Cairo station/01b_spacestation.