man, that intro screen is totally misleading!! i was expecting a 3d bullet hell, or something like starfox 64, but the game is in top down view (not that i dislike it but again, is a little misleading ), im coming from your post, so i will stick to the format that you proposed :
before i begin, i'm going to tell you that i'm writing this because you wanted feedback, and if the feedback is not sincere you will not have the chance to improve, i could just have wrote,
great game! ,i liked the music, and that's it but where is the learning in that??
it may seem like im trashing the game, but no. one thing is to say you did this wrong or i don't like what you did, and other thing is to say , you did this, but you can improve it in this or that way...
- AI : the enemies just ran into you, i only lost health when i hit them myself, i would have preferred just one well done enemy type, that the generic ones that are into the game (at least put a material into the models lol), their movement was ok, but they not presented a challenge, maybe you could improve that by making the AI movement with predefined patterns, like pac-man, whatch this video to know what im talking about
it has a little intro, but around the 5 minute mark it starts talking about the AI and its patterns.
- Player movement : i'm really curious about the code for the player movement, the ship moves, but at the same time shakes a lot, like if there was some clamped value or you had left out a variable that resets every time you move, anyway, you could move , but the movement was not smooth (the aim with the mouse worked perfectly), if you show me the code i can help you with the movement.
- Weapon system : i really didn't see this in the game, i picked up some power ups but most of them were health or the level up one. my advice is that you can instead of putting spheres that look like the enemies with illegible text (again, you could just drop a material into the spheres), you could have used a SPRITE to communicate what the power up means (since you are in a top down view, it's almost 2d basically) i mean, you do had an artist in your team right??
to quote you in a reply form other post "Yea our artist have unbelievable talent. " then why didn't he/she use it??
- Theme : i maybe have missed this, so i'm not going to talk about it.
- Overall visuals (Main Menu, and Player ship) : ups, i already mixed this with the other answers.
i really liked the music of the game, no complains there, serves the purpose and fits the intention of the game.