敌方飞机有大中小3种, 速度分别为高中低3种速度 → 计算题（十以内加法乘法）速度随等级变高而变快
消灭小飞机需要1发子弹, 中飞机需要8发子弹, 大飞机需要2发子弹 → 题目对应计算结果为血量，只要击中就可以消除题目
每消灭一道计算题得1000分，游戏根据分数来逐步提高难度, 难度提高表现为, 题目数量增加, 降落速度加快
将敌机改为题目后，需要修改碰撞检测
绘制图形碰撞检测参考代码：
import pygame, sys, time
from pygame.locals import *
import random
import math


#Colors
colorRed=pygame.Color(241,59,62)
colorPurple=pygame.Color(200,254,249)
colorBlue=pygame.Color(52, 207, 235)
colorGreen=pygame.Color(100,182,100)
colorWhite=pygame.Color(255,250,250)
colorBlack=pygame.Color(0,0,0)
colorOrange=pygame.Color(242,164,0)
colorBrown=pygame.Color(148,103,58)

#Dimensions
w=800
h=600
pygame.init()
fpsClock=pygame.time.Clock()
screen=pygame.display.set_mode((w,h))
pygame.display.set_caption ('SUMO')
centerX=w//2
centerY=h//2

#Stage
stageR=250
def stage (centerX,centerY):
   # stage (centerX,centerY) - creates a stage with given centerpoint
    pygame.draw.circle(screen, colorBlue, (centerX,centerY),stageR)

#Character 1
xR=int((stageR//10))
x1=int(centerX-(stageR*0.8))
y1=centerY
x1_dir=0
y1_dir=0
def char1 (x1,y1):
    #char1 (x1,y1) - creates char1 at given coordinates
    pygame.draw.circle(screen, colorRed, (x1,y1),xR)
print (x1)
print (centerX)

#Character 2
x2=int(centerX+(stageR*0.8))
y2=centerY
x2_dir=0
y2_dir=0
def char2 (x2,y2):
    #char2 (x2,y2) - creates char1 at given coordinates
    pygame.draw.circle(screen, colorGreen, (x2,y2),xR)





while True:
    screen.fill(colorBlack)
    for event in pygame.event.get():
        #Game Exit
        if event.type== QUIT:
            pygame.quit()
            sys.exit()

    distance=math.hypot(x1-x2,y1-y2)
    if distance <= 2*xR:
        print ("HIT")

    keys = pygame.key.get_pressed()

    if keys[K_d] or keys[K_a]:
        x1_dir += 0.1 if keys[K_d] else -0.1
    else:
        x1_dir *= 0.98

    if keys[K_w] or keys[K_s]:
        y1_dir += 0.1 if keys[K_s] else -0.1
    else:
        y1_dir *= 0.98

# -------------------- CHAR2 MOVEMENT --------------------

    if keys[K_RIGHT] or keys[K_LEFT]:
        x2_dir += 0.1 if keys[K_RIGHT] else -0.1
    else:
        x2_dir *= 0.98

    if keys[K_UP] or keys[K_DOWN]:
        y2_dir += 0.1 if keys[K_DOWN] else -0.1
    else:
        y2_dir *= 0.98


    stage (centerX,centerY)
    char1 (round(x1),round(y1))
    char2 (round(x2),round(y2))
    x1+=x1_dir
    y1+=y1_dir
    x2+=x2_dir
    y2+=y2_dir
    pygame.display.update()
    fpsClock.tick(60)