Rescue Rover Saved game format
From ModdingWiki
Rescue Rover Saved game files are simple files used to store the player's progress in Rescue Rover Only one game is saved, SAVEGAME.ROV. The file is sixty bytes in length, two bytes for each level of Rescue Rover.
The first byte stores the number of tries a player has attempted for a level (After 255 tries this will wrap around to zero.) the second byte stores whether a level is done, $00 is incomplete, $80 complete. (the highest bit is changed.)