Hello, I just finished the game! It took me 20h50m and I think I got 100% of the items.
I found it challenging, especially figuring out how to get some of the optional items. But I didn't have any trouble in terms of bugs or anything like that.
I thought the game was really amazing. The design of the world was so interesting and full of surprises. Every area felt fresh and new, even the ones at the very end of the game. I loved how it progresses from "normal" video game areas like jungle, cave, mountain, etc. to strange alien structures. The atmosphere in some of the later areas was really cool. The powerups were great and kept surprising me and overall the mechanics were really interesting. I think this is one of my favourite games I've played in a long while.
There isn't really anything I didn't like. It is easy to lose a lot of progress when you die, which is sometimes frustrating, but that's also part of what makes the game interesting. There is a lot of tension in parts like the escape sequences after many of the bosses. When I got frustrated, I just had to take a break and come back later.
One thing I wanted to comment on is that the game progression feels fairly linear. It's not truly linear because there are different paths to explore within each area, and you can backtrack to get things you missed. But the overall structure feels like you end up going through the areas in a set order. Usually, I prefer exploration games that are very open-ended, and I get bored when they are too linear. But I never got bored with discovering more of the world in this game. So I don't think the game being somewhat linear is a bad thing. In fact, I think you did an amazing job and this game shows how good this kind of linear structure can be. But if you ever want to make a game with a more "open world" style I would love to see it.
If you want to put me in the credits, my name is Sylvie and I would want a blue and purple gradient like this: