Somethings that's been a fun idea for the game is discovering creatures and rare objects. so when you encounter something new to your character you will get a notification saying "Congrats! you discovered [Insert thing here]!" This could give like a slight pokemon vibe of discovering all the things in the game, from rare guns, vehicles and armor types, to rare buildings, kaiju, or even rare plants and locations. It could make exploring really fun discovering all the different things the devs might hide in the game, maybe even make sort of a race to find the rarest thing of all first.