Gameplay isn't bad, but isn't anything spectacular, either. The game doesn't need a tutorial, but more information about what to expect as you play would be good, especially about how dying does not mean game over, but rather will take you to the shop so you can upgrade.
The opening frames that tell the backstory need improvement. I took the liberty of editing them for you. Each paragraph corresponds to the individual frame, in sequence:
“The thirty-third eclipse of the sun will mark the start of a new era and the confluence of the worlds. Doors to dark worlds will open and a great invasion will begin.” Only a few believed this ancient prophecy.
One of those who believed in the coming of this dark new era was Varlow the Wise, a great and powerful wizard. To prepare the world for the great invasion, he founded a special guild in secret mountain caves. He named this guild the Astral Guard.
Members of the Astral Guard strove to improve their spellcasting skills, their control over the primal forces of magic, and their intellect. This rigorous training took place daily, from dawn to dusk, from the day each member was born until the day they died. The guild produced very powerful, wise, and loyal people. No member of the guild ever betrayed the cause.
The day foretold by the prophecy finally came. At the height of the solar eclipse, thousands of portals opened simultaneously opened all over the world. Hordes of dark creatures spilled out of the portals. The world’s armies and militias could not contain the offensive, and were overrun within the first hour. Panic spread throughout all the lands. The world was unprepared because so few believed in the prophecy.
But the Astral Guard believed and was prepared to fight back. I am Zen, a member of the Guard. Eight days have passed since the start of the great invasion. We have lost so much and so many, but we strive to resist the invaders. I believe that we can stop the destruction and reclaim our world.