你可以使用Python中的pygame库来实现这个功能。下面是一个示例代码：

import pygame
import random

# 初始化pygame
pygame.init()

# 定义窗口尺寸
screen_width = 800
screen_height = 600

# 创建窗口
screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("射击游戏")

# 定义子弹的属性
bullet_width = 10
bullet_height = 10
bullet_color = (255, 0, 0)
bullet_speed = 5

# 定义子弹的初始位置和状态
bullet_x = 0
bullet_y = 0
bullet_state = "ready"

# 定义敌人的属性
enemy_width = 50
enemy_height = 50
enemy_color = (0, 255, 0)
enemy_speed = 2

# 定义敌人的初始位置和状态
enemy_x = random.randint(0, screen_width - enemy_width)
enemy_y = random.randint(50, 150)
enemy_state = "alive"

# 定义玩家的属性
player_width = 50
player_height = 50
player_color = (0, 0, 255)
player_speed = 3

# 定义玩家的初始位置
player_x = (screen_width - player_width) // 2
player_y = screen_height - player_height

# 定义键盘按键对应的动作
KEY_LEFT = pygame.K_LEFT
KEY_RIGHT = pygame.K_RIGHT
KEY_SPACE = pygame.K_SPACE

# 用于退出游戏循环的标志
running = True

# 游戏循环
while running:
    screen.fill((0, 0, 0))
    
    # 处理事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == KEY_LEFT:
                player_x -= player_speed
            elif event.key == KEY_RIGHT:
                player_x += player_speed
            elif event.key == KEY_SPACE and bullet_state == "ready":
                bullet_x = player_x + player_width // 2 - bullet_width // 2
                bullet_y = player_y
                bullet_state = "fire"
    
    # 更新子弹的位置
    if bullet_state == "fire":
        bullet_y -= bullet_speed
        pygame.draw.rect(screen, bullet_color, (bullet_x, bullet_y, bullet_width, bullet_height))
        if bullet_y < 0:
            bullet_state = "ready"
    
    # 更新敌人的位置
    if enemy_state == "alive":
        enemy_x += enemy_speed
        pygame.draw.rect(screen, enemy_color, (enemy_x, enemy_y, enemy_width, enemy_height))
        if enemy_x > screen_width - enemy_width or enemy_x < 0:
            enemy_speed = -enemy_speed
    
    # 检测碰撞
    if bullet_state == "fire" and enemy_state == "alive":
        if bullet_x + bullet_width > enemy_x and bullet_x < enemy_x + enemy_width and bullet_y < enemy_y + enemy_height:
            bullet_state = "ready"
            enemy_state = "dead"
    
    # 更新玩家的位置
    pygame.draw.rect(screen, player_color, (player_x, player_y, player_width, player_height))
    
    # 刷新屏幕
    pygame.display.flip()

# 退出pygame
pygame.quit()

这个示例代码创建了一个简单的射击游戏，玩家可以使用左右箭头键来控制玩家的移动，使用空格键来发射子弹。子弹会从玩家的位置射出，并且会射中敌人后消失。敌人会在屏幕上左右移动，当敌人被射中后，会消失。请注意，这只是一个基本示例，你可以根据自己的需求进行修改和扩展。