So, great idea, but the game was very hard, there were a lot of enemies, and they would not die easily, just reducing the spawns of enemies at the beginning, and spawning more, the more the player has upgrades would help a lot. And the shield was pretty much useless, I couldn't block nothing with it. The enemies were also much faster than the player, this becomes an issue when that is, in theory, the weakest enemy of your game. Escaping them was pretty much impossible, they would just box you and beat you to death, the player should be able to be even, or even higher in strength compared to the first enemies he encounters, even Dark Souls does that until the player gets a hang of the controllers and things like that. The idea of upgrading your enemies alongside the player is okay in itself, the problem is when that happens with every upgrade he gets, it's like he's not leaving square one at all, like when you get a Health upgrade, but your enemies get a Damage upgrade, so basically it's a zero sum game, where nobody really gets anything at all.