It is always good to see a game with a beginning, middle, and end, especially one as large as this.
I feel like the CC-BY/CC-BY SA licence terms of some of the assets you were making use of aren't quite fulfilled by just linking to the users' profile pages on Open Game Art - among other things, the specifics of the licence terms require copyright notices, etc. and a link directly to the work. It can also be difficult to identify which bits were used when a user has uploaded a lot of things.
I found myself wishing that the game didn't end as soon as I killed the large boss - it would have been nice to continue to explore afterward.
Something to note - since you uploaded a single loose binary, any executable permissions needed to let this run out of the box on a Linux machine were lost. It would be a good idea to make note on your game page that Linux users will need to set executable permissions on the game via the file properties dialogue in their favourite file browser.
This was a lot larger than I was expecting! There was a good sense of exploration and pacing as newer and larger enemies/enemy combinations were introduced.Well done!