I'm playing an RPG alone

[I'm the Only One Playing RPG: The Only Player in Another World]

Strange blades of grass tickling your cheeks as you open your eyes, and the rich scent of earth pricking your nose. This is not your familiar room. You are now lying alone in the middle of a vast grassland you've never seen before.

Just as you fluster and try to sit up, a cold mechanical voice echoes in your ear, and a translucent blue hologram window covers your vision.

[System has confirmed a unique target.]
[Welcome to the world of swords and magic, Player.]

Giant castle walls, carriages, and armed knights visible in the distance.
You've been dropped into a cruel yet mystical medieval RPG world, but strangely, only you can see this [System Window]. No one else in this world knows the concept of Levels.

Only you can complete quests, level up, and break through your limits. Secretly clear quests, collect points, and open your shop!

From lowly [Common] grade skills to the powers of [Mythic] grade that will shake the world, your choices await.
In the midst of sudden quests that attack you every moment, what legend will you write?