While a fun and well made game, it had a lot of problems syncing up it's gameplay with the world and tone that you tried to convey. As a solid Metroidvania-styled game the powerups were well spaced out, the map design was tight and didn't make you backtrack very far, and the few secrets and extra life goodies were a nice incentive to explore the level you designed. In all of those aspects it was a great game.
However if you intend to make a serious and emotional story in a post apocalyptic world you need to have the powerups and story match a better. It was sort of silly that the generic survivor was suddenly learning how to double jump, wall jump and use energy explosions. It would have made much more sense to have gained some technology, like a short burst jetpack or hiking gear to imitate the abilities that you "learned", and it would have been much better if you had just gotten rid of the energy explosion entirely. Aside from the one boss fight it's never needed and the gun is so versatile at killing enemies I never needed to use the energy attack at all. Not to mention it would have saved you all the bother of making enemies drop orbs to collect, which had a rather annoying process of needing to trail after you after you picked them up for them to actually be collected. For future references, either have that sort of thing home in on your character the second the enemy dies, or have it be something the character needs to pick up. Don't do both.
Lastly the story is frankly kind of weak. I won't give anything away so I don't spoil it for anyone, but suffice to say it is sort of bizarre how you end up going all Rambo on the facility at the end, the boss comes right out of nowhere, creating more questions as to just how or why they would make that thing, much less how it can't be hurt by gunfire or grenades during the first part, but it can later on, and finally the ending is just sort of anticlimactic. It's just an image that kind of vaguely hints at hope, but it doesn't actually give a proper ending to anything.
I did enjoy your game, but it's the whole package that makes a good game into a great game. It was fun, but it will be ultimately forgettable as it fails to do anything new or gripping with it's gameplay, story and characters.