Some random ideas for the overworld/realms.
When you manage to initiate a creature battle by walking against the overworld creature sprites’ back, you’ll do a surprise attack, likewise if a creature hits the player’s back they do a surprise attack.
Creatures have different/random lines of sight, when a creature notices you an icon/effect shows this.
Some creatures give up chasing you after a few moves.
Some creatures alert other nearby creatures of your presence in the current room, attracting them.
Some rare creatures try to avoid you, this indicates they carry something of more value, if they manage to leave the players’ line of sight they vanish completely.
Some creatures have invisibility frames, alternating between visible-invisible.
Regarding new tiles:
Quicksand/Swamp: Every tile you move, enemies get to move twice. Creatures are slowed down by these tiles as well, making hunting more fun with creatures that try to avoid you, you can now drive them towards these tiles.
Bush/Cave: safe place, creatures that were following you now stop following you.
Please pitch in with your overworld ideas as well! Let’s spruce up exploration and add in a layer of preperation as well!