Error while testing: "TypeError: game.check is not a function" rock, paper scissors JS

[Carrosen]

Problem

I get an error saying game.check is not a function.

Background

Used material for fizzbuzz Javascript challenge as template.
The error came up as after I changed the naming of functions and values to fit my game.
I feel like my whole code is kind of a mess, I apologize in advance

Spec

describe('Game', () => {
    let game = new Game
    let Player1 = ('button1').value
    let Player2 = ('button2').value

    describe('Player1 wins', () => {

        it('returns Player1 is the winner if Player1 enters "rock" and Player2 enters "scissors"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player1 is the winner!")
        })

        it('returns Player1 is the winner if Player1 enters "paper" and Player2 enters "rock"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player1 is the winner!")
        })

        it('returns Player1 is the winner if Player1 enters "scissors" and Player2 enters "paper"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player1 is the winner!")
        })
    })


    describe('Player2 wins', () => {

        it('returns Player2 is the winner if Player2 enters "rock" and Player1 enters "scissors"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player2 is the winner!")
        })

        it('returns Player2 is the winner if Player2 enters "paper" and Player1 enters "rock"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player2 is the winner!")
        })

        it('returns Player2 is the winner if Player2 enters "scissors" and Player1 enters "paper"', () => {
            expect(game.check(Player1, Player2)).to.eql("Player2 is the winner!")
        })
    })

    describe('Its a tie!', () => {
        
        it('returns Its a tie! if Player1 == Player2', () => {
            expect(game.check(Player1 == Player2)).to.eql("Its a tie!")
        })

    })

})

Implementation code

game.js

function Game() {
    let Player1 = ('button1').value
    let Player2 = ('button2').value
    this.check = (Player1, Player2)
  
            if (Player1 === Player2) {
                return 'Its a tie!';
            } 
        
            else if ((Player1 === "rock") && (Player2 === "scissors")) {
                return 'Player1 is the winner!';
            }
            else if ((Player1 === "rock") && (Player2 === "paper")) {
                return 'Player2 is the winner!';
            }
            else if ((Player1 === "paper") && (Player2 === "rock")) {
                return 'Player1 is the winner!';
            }
            else if ((Player1 === "paper") && (Player2 === "scissors")) {
                return 'Player2 is the winner!';
            }
            else if ((Player1 === "scissors") && (Player2 === "paper")) {
                return 'Player1 is the winner!';
            }
            else if ((Player1 === "scissors") && (Player2 === "rock")) {
                return 'Player2 is the winner!';
            }
            else {
                return 'That is not the game pal, try "rock", "paper" or "scissors"';
            }
    }

application.js

  it('clicking on the "Check" button', async () => {
    await browser.fillIn("input[id='value1']", { with: "rock" })
    await browser.clickOnButton("#button1")
    await browser.fillIn("input[id='value2']", { with: "rock" })
    await browser.clickOnButton("#button2")
    await browser.clickOnButton("#button3")
    let content = await browser.getContent("[id='display_answer']")
    expect(content).to.eql('Its a tie!');

  })

How did you try to solve the problem?

I think it has to do with the naming of different values, so I tried to figure out what and changed a bunch of them.
I have tried to google the error and on other RPS games, going through the material once again. I think it's more than one typo or wrong naming problem here so I found it hard to figure it out.