An interesting idea, but there were a few problems that, when combined, made this pretty unplayable. 

One of the bigger issues was the player would sometimes get stuck on a tile when moving, so it seemed like there was an invisible wall. This is a shot in the dark, but my guess is you used a "Tilemap Collider 2d" component for the tiles. If you did,  adding a "Composite Collider 2D" to that same tilemap, and checking "Used by Composite" on the Tilemap Collider would solve this issue (I could be wrong here!)

The second issue was there was no indication that the reload times were random, so it just seemed like the gun wouldn't work sometimes. Sometimes I couldn't shoot for so long, I couldn't get rid of the 4th enemy, and I would jump into him since the jump was so high. 

Fixing the collisions, tweaking the jump / movement speed, and adding an indication for the reload time would really help this game. You have a good foundation here though, keep it up!

The game feels a little too slow to be enjoyable for me. I like the concept behind it. 

The controls were a bit finicky, but I liked the level of polish in some areas like the trigger whenever you fire the gun and your flailing arms.