Why is cuphead so difficult?

We all have played the toughest game darksouls at least once in our#life but some of us were able to completethe game.#From sofyware were able to give us the toughest game ever but there is now another game with a much more simple conceptand retrobackground sound.
‘Cuphead’,name is a little wierdbut perfectly suits the concept of game.Thestory goes like this,two brothers‘cuphead’ and’mugman’ goes to a casino and deals with the devilthat if they will #lose,their soul will be devils.Asyou expect they losebut they the devilgives them a list of names and tells them that if they want to save their soulsthey have to bring each soul written in list to him.
So what makes it so difficult,simple you are just a small person with cupshaped head and you can only shoot with your fingersand special attack can only be triggered by collecting red orbsduring fighting the boss and boss are huge with 3 level of transformation each one with differentpower and best part it is a 2d game but you will love it and i am sure of it .
Cuphead has retro music reminding of oldage games but it comes with totally new #convept
And some great characters too.Cuphead is a game that will push you to your limitsand forve you to ragequit .This game is also a motivation as before its release everyonewas saying that it was going to be a flopgame but after release it became one of the toughestgames ever.It is developed be indiecompany.This games bosses are now so frighting but are very difficultto kill and have greatsuper moves which can not be predicted.This game is awesome and everyone should play it atleast once in their life.
Here are its pc req:
Operating System: Windows 7.
Processor: Intel Core2 Duo E8400, 3.0GHz or AMD Athlon 64 X2 6000+, 3.0GHz or higher.
Memory: 2 GB RAM.
Graphics: Geforce 9600 GT or AMD HD 3870 512MB or higher.
DirectX: Version 9.0.
Storage: 20 GB available space.