Hey, this is a pretty cool concept! I like the idea of literally drawing out spells. It definitely makes me feel more mage-like when there's a little more to the magic than a single button press.
To be honest though, I kinda got misled at the start, thinking that I was going to be finding different runic symbols via studying the visuals in the game world rather than obtaining them as pickups. At the start, I saw all those different runes, and tried drawing them (finding the restart rune in the process), but I was a bit disappointed that they didn't do anything (aside from the one that ends up being first spell you find). It would've been a cool way to reward a player's curiosity.
All in all, this was cool game. I have couple of other thoughts, but I don't want this to turn into an extensive review (lol). I can't help but wonder what else you could do with this mechanic, but I digress.
Btw, I like the pixel art too. Simple but nice to look at. 👍