My 2D megaman Game

Currently im learning UE4 by making a simple Game, i love megaman so much, so i decided to recreate it. But for now, i have 1 problem is that when i package the game, the game’s size is so big (400mb for this game in the video clip, WOW). Can anyone tell me how to reduce the game’s size? Btw, here is my game.
https://www.youtube.com/watch?v=pniyDW8I9bE