manual:

Objects are stored by their indices. Therefore levels, scripts, and objects must not change between game_save and game_load, with exception of level entities. All .._create and .._remove calls, except ent_create and ent_remove, must be executed before the first game_save or game_load call. When the script was changed in any way, or when the number of objects is different, game_load will fail.

maby use

SV_POINTERS

ore sav in a .txt file white file_asc_write/file_var_write