C# Simple game for 2 players

/* Some simple game I created with my class-mate for school. Requirement is a simple Form1-Window with the size 378*400 . Planned is to add networking to this.
Edit: I totally forgot: You have to manually add the Paint-Event and KeyDown-Event. For this just go to the properties of your windows and click on the small sign that looks like a thunderbolt. Find the two events and (if the code is already pasted) you can select the Event next to it*/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace BubbleWars
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        Timer timer = new Timer();
        Random random1 = new Random();
        Random random2 = new Random();
        Random random3 = new Random();
        Random random4 = new Random();

        short headX = 100; //player position X
        short headY = 100; //player position Y
        short head2X = 200;
        short head2Y = 200;
        byte circleW = 10; //Breite des Kreises
        byte circleH = 10; //Höhe des Kreises
        int score = 0; //Punktzahl natürlich!
        int score2 = 0;
        int rndFutterX = 0; //random number for food x-coordinate
        int rndFutterY = 0; //random number for food y-coordinate
        int rnd2FutterX = 0;
        int rnd2FutterY = 0;

        byte richtung = 0; //variable for direction
        byte richtung2 = 0;

        private void Form1_Load(object sender, EventArgs e)
        {
            rndFutterX = random1.Next(0, 35);
            rndFutterY = random2.Next(0, 35);
            rnd2FutterX = random3.Next(0, 35);
            rnd2FutterY = random4.Next(0, 35);
            rndFutterX = rndFutterX * 10;
            rndFutterY = rndFutterY * 10;
            rnd2FutterX = rnd2FutterX * 10;
            rnd2FutterY = rnd2FutterY * 10;

            this.Paint += Form1_Paint; //Aufruf Paint-Event
            timer.Interval = 1000;
            timer.Tick += new EventHandler(Update);
            timer.Start();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            SolidBrush playerBrush = new SolidBrush(Color.Red);
            Graphics grafik = this.CreateGraphics();
            Rectangle circle = new Rectangle(headX, headY, circleH, circleW);
            grafik.FillEllipse(playerBrush, circle);

            SolidBrush player2Brush = new SolidBrush(Color.DarkRed);
            Graphics grafik2 = this.CreateGraphics();
            Rectangle circle2 = new Rectangle(head2X, head2Y, circleH, circleW);
            grafik2.FillEllipse(player2Brush, circle2);

            e.Graphics.DrawRectangle(Pens.Black, rndFutterX, rndFutterY, 10, 10);
            e.Graphics.DrawRectangle(Pens.Black, rnd2FutterX, rnd2FutterY, 10, 10);
        }

        private void Update(object sender, EventArgs e)
        {
            if (richtung == 1)
            {
                headY += 10;
                this.Refresh();
            }
            if (richtung == 2)
            {
                headY -= 10;
                this.Refresh();
            }
            if (richtung == 3)
            {
                headX -= 10;
                this.Refresh();
            }
            if (richtung == 4)
            {
                headX += 10;
                this.Refresh();
            }
            if (richtung2 == 1)
            {
                head2Y += 10;
                this.Refresh();
            }
            if (richtung2 == 2)
            {
                head2Y -= 10;
                this.Refresh();
            }
            if (richtung2 == 3)
            {
                head2X -= 10;
                this.Refresh();
            }
            if (richtung2 == 4)
            {
                head2X += 10;
                this.Refresh();
            }
            //snake on corner
            if (headY == 360 || headY == -10 || headX == 360 || headX == -10)
            {
                timer.Stop();
                MessageBox.Show("Game Over. Player 1 ran into a wall.\nPlayer 1 score: "+score+"\nPlayer 2 score: "+score2);
            }
            if (head2Y == 360 || head2Y == -10 || head2X == 360 || head2X == -10)
            {
                timer.Stop();
                MessageBox.Show("Game Over. Player 2 ran into a wall.\nPlayer 1 score: " + score + "\nPlayer 2 score: " + score2);
            }
            if (head2Y == headX && head2Y == headY)
            {
                timer.Stop();
                MessageBox.Show("Game Over. You idiots crashed into each other!\nPlayer 1 score: " + score + "\nPlayer 2 score: " + score2);
            }


            //snake on food
            if (headY == rndFutterY && headX == rndFutterX)
            {
                rndFutterX = 10 * random1.Next(0, 35);
                rndFutterY = 10 * random2.Next(0, 35);
                score += 1;
                if (timer.Interval > 250)
                {
                    timer.Interval = timer.Interval - 250;
                }
                if (timer.Interval > 100 && timer.Interval <= 250)
                {
                    timer.Interval = timer.Interval - 50;
                }
                if (timer.Interval > 20 && timer.Interval <= 100)
                {
                    timer.Interval = timer.Interval - 20;
                }
                if (timer.Interval > 2 && timer.Interval <= 20)
                {
                    timer.Interval = timer.Interval - 2;
                }
            }
            if (head2Y == rndFutterY && head2X == rndFutterX)
            {
                rndFutterX = 10 * random1.Next(0, 35);
                rndFutterY = 10 * random2.Next(0, 35);
                score2 += 1;
                if (timer.Interval > 250)
                {
                    timer.Interval = timer.Interval - 250;
                }
                if (timer.Interval > 100 && timer.Interval <= 250)
                {
                    timer.Interval = timer.Interval - 50;
                }
                if (timer.Interval > 20 && timer.Interval <= 100)
                {
                    timer.Interval = timer.Interval - 20;
                }
                if (timer.Interval > 2 && timer.Interval <= 20)
                {
                    timer.Interval = timer.Interval - 2;
                }
            }
            if (headY == rnd2FutterY && headX == rnd2FutterX)
            {
                rnd2FutterX = 10 * random3.Next(0, 35);
                rnd2FutterY = 10 * random4.Next(0, 35);
                score += 1;
                if (timer.Interval > 250)
                {
                    timer.Interval = timer.Interval - 250;
                }
                if (timer.Interval > 100 && timer.Interval <= 250)
                {
                    timer.Interval = timer.Interval - 50;
                }
                if (timer.Interval > 20 && timer.Interval <= 100)
                {
                    timer.Interval = timer.Interval - 20;
                }
                if (timer.Interval > 2 && timer.Interval <= 20)
                {
                    timer.Interval = timer.Interval - 2;
                }
            }
            if (head2Y == rnd2FutterY && head2X == rnd2FutterX)
            {
                rnd2FutterX = 10 * random3.Next(0, 35);
                rnd2FutterY = 10 * random4.Next(0, 35);
                score2 += 1;
                if (timer.Interval > 250)
                {
                    timer.Interval = timer.Interval - 250;
                }
                if (timer.Interval > 100 && timer.Interval <= 250)
                {
                    timer.Interval = timer.Interval - 50;
                }
                if (timer.Interval > 20 && timer.Interval <= 100)
                {
                    timer.Interval = timer.Interval - 20;
                }
                if (timer.Interval > 2 && timer.Interval <= 20)
                {
                    timer.Interval = timer.Interval - 2;
                }
            }
        }


        public void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Down)
            {
                richtung = 1;
            }
            if (e.KeyCode == Keys.Up)
            {
                richtung = 2;
            }
            if (e.KeyCode == Keys.Left)
            {
                richtung = 3;
            }
            if (e.KeyCode == Keys.Right)
            {
                richtung = 4;
            }
            if (e.KeyCode == Keys.S)
            {
                richtung2 = 1;
            }
            if (e.KeyCode == Keys.W)
            {
                richtung2 = 2;
            }
            if (e.KeyCode == Keys.A)
            {
                richtung2 = 3;
            }
            if (e.KeyCode == Keys.D)
            {
                richtung2 = 4;
            }
        }
    }
}