I've played it multiple times and even challenged myself to see how fast I can beat it, beating it in under 3 minutes by using the plus attack to decrease gravity to skip the last section. The puzzle bit of the game is fun! There's so much potential with the ability to conjure objects or expression using letters, I'm already thinking of a few ideas such as a boss where you conjure its weaknesses (maybe physically with a weapon or mentally with mean expressions haha) and secret areas to explore (like its own version of a cheat code). Maybe an enemy interaction where if one gets close to each other, they start forming words too? and become a monstrosity.
The bugs I've experienced every time I played is going between the second and third section of the game (where you collect KE and Y from the room above), the transition is always awkward, sending me into a loop that brings me back to the bottom room. Another bug is the letter I has its projectile based on its shooter orientation, which means as the letter I shoots and rotates, the bullet also rotates based on where I is currently looking now. This made it the hardest enemy of the game by far.
Great art work as well! Love the little character with the triangle body, and using inspiration from my favorite 2D video game! And the extra detail of the last segment using numbers to help me get across, shows that math truly gets me across everything :)
If I had to be strict, here some things I would improve on.
There should be more interactable stuff, I believe there were only 3 things interactable, the guides, the checkpoints and then just the one lever to reveal the bookshelf. Maybe another use would be exposing a letter? To get you to the next room. I think a dark room where you have to light up torches or lanterns would be good possibly, and maybe notes or books on the floor as hints if they can't figure out the word combination.
I think a small story would be good to have too! Small story bits here and there and maybe a cliffhanger, like instead of the end screen simply displaying end, maybe theres a corrupted number,a large door, a boss hint, before fading to black. Now instead of leaving a player with 'oh, thats the end', now they'll want more because they're pondering questions.
Knockbacking when you attack would be good to have as well as the enemies sometimes can continue advancing as you attack.
Small nitbit, the black outlines on some of the sprites are inconsistent in size. I know consistency is a good thing in game art, as without it, some art piece may be out of place. Examples are the stands for the book, as well as some of the letters, such as the E compared to the ND at the ending room.
Placing the wordholder I personally would bring to the bottom left, so as to not obstruct my weapon type (even if its minor).
Of course, I didn't take into account how much time you had and your current development experience, so some of these may be too obvious which I'm sorry!
Overall, fun experience! Hopefully this was a helpful review to guide you on your further games! If you plan to continue expanding on this, I can't wait to see it! And since you use Godot, I can help you out as well for anything in the future with programming.