Idea: biome changes.
I was thinking, that every once in a while there would be a biome change.
These were a few biome ideas I had.
DESERT
GROUND: SAND
ANIMAL: SCORPION - HOSTILE
OBSTACLES: ROCKS and CACTI (deal damage)
FOREST
GROUND: GRASS
ANIMAL: FOX - NEUTRAL
OBSTACLES: ROCKS, TREES
MOUNTAIN
GROUND: ROCK
ANIMAL: MOUNTAIN GOAT
OBSTACLES: ROCKS