I didn't see any issues with SPAG, I thought that for the most part, your grammar and spelling were on point. If you're interested in improving SPAG and sentence structure, I just wanted to give a shoutout to Gryphon's sentence workshop.
Gryphon held this sentence structure workshop about a month ago, where he had people submit samples of their writing for critique and line-by-line edits. I learned about making line-edits there, and I'll drop the link here because I thought it was really good.
Gryphon's sentence structure workshop
I learned a lot there, and I highly encourage you to read through everyone's submissions and the critique given there, if you haven't already.
Once you've read through some line-edits, make your own! Go through the passage, and see things that you might want to improve, and I promise you, do this 2 or 3 times and it will really pay off! Keep the following in mind when editing: grammar, sentence structure flow, information delivery, characterization, showing vs telling, setting tone, and tenses.
I really enjoyed this story. It was really amazing, and I thought the world building was really cool.I really hope you make this into a full story game, I thought the failed experiment writing, how his eyes burned into his sockets, that was really cool. I recently watched Arcane, and this failed experiment was reminiscent of arcane, in a good way, like this passage matched arcane's vibe. It felt like Viro is Jace, and he becomes Viktor when he gets the accident. I also see hints of Professor Heimerdinger in Viro's caution in banning Eclipse magic.