最终效果：

完整视频：

Code：
settings.py

RES=WIDTH,HEIGHT=800,600
FPS=60

main.py

import pygame as pg
from settings import *
import sys

class Game:
    def __init__(self):
        pg.init()
        self.screen=pg.display.set_mode(RES)
        self.clock=pg.time.Clock()
        self.DOWN_KEY,self.UP_KEY=False,False
        self.x,self.y=260,200

    def update(self):
        pg.display.flip()
        self.clock.tick(FPS)
        pg.display.set_caption(f'{self.clock.get_fps():.1f}')


    def draw(self):

        self.screen.fill('black')

        self.cursor()

        self.text("aaaaa", (255,255,255), (300,200))
        self.text("bbbb", (255,255,255), (300,300))
        self.text("cccc", (255,255,255), (300,400))


    def text(self,text,color,pos):
        font=pg.font.Font('8-BIT WONDER.TTF', 35)
        img=font.render(text,True,color)
        self.screen.blit(img, pos)


    def cursor(self):


        if self.DOWN_KEY and 200<=self.y<400:
            self.y+=100
            self.DOWN_KEY=False
        if self.UP_KEY and 400>=self.y>200:
            self.y-=100
            self.UP_KEY=False

        self.text("x", "red", (self.x,self.y))


    def events(self):
        for event in pg.event.get():
            if event.type==pg.QUIT:
                pg.quit()
                sys.exit()
            if event.type==pg.KEYDOWN:
                if event.key==pg.K_DOWN:
                    self.DOWN_KEY=True
                if event.key==pg.K_UP:
                    self.UP_KEY=True


    def run(self):
        while True:
            self.events()
            self.update()
            self.draw()


if __name__ == "__main__":
    game=Game()