pygame setting borders?

[Windspar]

1. Need to learn rects. This will do a lot of the work for you.
2. Vector2 will keep your floats and handle different math for you.
3. pygame has over 400 builtin colors.
4. Use pygame.time.Clock over pygame.time.delay. This will lead to smoother movement and constant movement
5. Use delta from pygame.time.Clock to move player smoothly. delta = clock.tick(fps)

Example how I would do it.

import pygame

class Player:
    def __init__(self, rect, color):
        # Player position
        self.rect = pygame.Rect(rect)
        # Hold floats since rects are only ints
        self.center = pygame.Vector2(self.rect.center)
        self.vel = 10 * 0.01
        self.color = color

    def collision(self, walls):
        collided = []
        for wall_rect in walls:
            if wall_rect.colliderect(self.rect):
                collided.append(wall_rect)

        if len(collided) > 0:
            # Keep smooth movement
            center = self.center - pygame.Vector2(int(self.center.x), int(self.center.y))
            for wall_rect in collided:
                # Get what over lapping
                clip_rect = self.rect.clip(wall_rect)
                # Check if wall is still overlapping.
                # Needed if collided with more than one wall.
                # Else player would start jumping up and down the walls
                if clip_rect.w > 0 or clip_rect.h > 0:
                    # Take the smallest overlap and move player over
                    if clip_rect.w < clip_rect.h:
                        center.x = 0
                        if self.rect.centerx < wall_rect.centerx:
                            self.rect.right = wall_rect.left
                        else:
                            self.rect.left = wall_rect.right
                    else:
                        center.y = 0
                        if self.rect.centery < wall_rect.centery:
                            self.rect.bottom = wall_rect.top
                        else:
                            self.rect.top = wall_rect.bottom

            self.center = pygame.Vector2(self.rect.center) + center

    def move(self, direction, delta, walls):
        self.center += direction * delta * self.vel
        self.rect.center = self.center
        self.collision(walls)

    def draw(self, surface):
        surface.fill(self.color, self.rect)

def main():
    pygame.init()
    # Basic pygame setup
    pygame.display.set_caption("Example")
    main_surface = pygame.display.set_mode((600,500))
    rect = main_surface.get_rect()
    clock = pygame.time.Clock()
    delta = 0
    fps = 60

    # Game varaibles
    player = Player((290, 400, 20, 20), pygame.Color("yellow"))
    walls = [pygame.Rect(0, 0, 30, 500),
             pygame.Rect(570, 0, 30, 500),
             pygame.Rect(0, 470, 250, 30),
             pygame.Rect(350, 470, 250, 30),
             pygame.Rect(0, 0, 200, 30),
             pygame.Rect(400, 0, 200, 30),
             pygame.Rect(210, 0, 10, 30),
             pygame.Rect(230, 0, 10, 30),
             pygame.Rect(250, 0, 10, 30),
             pygame.Rect(380, 0, 10, 30),
             pygame.Rect(360, 0, 10, 30),
             pygame.Rect(340, 0, 10, 30),
             pygame.Rect(160, 30, 100, 200),
             pygame.Rect(340, 30, 100, 240),
             pygame.Rect(160, 130, 200, 140),
             pygame.Rect(180, 130, 100, 240),
             pygame.Rect(320, 130, 100, 240)]

    # Create a map surface 
    map_surface = pygame.Surface(rect.size)
    map_surface.fill(pygame.Color('gray50'))
    for rect in walls:
        map_surface.fill(pygame.Color("yellow"), rect)

    # Main loop
    running = True
    while running:
        # Event loop

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False

        keys = pygame.key.get_pressed()
        direction = pygame.Vector2(0, 0)
        if keys[pygame.K_LEFT]:
            direction.x -= 1

        if keys[pygame.K_RIGHT]:
            direction.x += 1

        if keys[pygame.K_UP]:
            direction.y -= 1

        if keys[pygame.K_DOWN]:
            direction.y += 1

        if direction != pygame.Vector2(0, 0):
            # Normalize for player is moving in a circle instead of a square.
            direction.normalize_ip()
            player.move(direction, delta, walls)

        main_surface.blit(map_surface, (0, 0))
        player.draw(main_surface)

        pygame.display.update()
        # Idle. delta is time between frames in milliseconds.
        delta = clock.tick(fps)

main()

---

Less error prone way is just return player back to old position.

---

class Player:
    def __init__(self, rect, color):
        # Player position
        self.rect = pygame.Rect(rect)
        # Hold floats since rects are only ints
        self.center = pygame.Vector2(self.rect.center)
        self.vel = 10 * 0.01
        self.color = color

    def collision(self, rect, walls):
        for wall_rect in walls:
            if wall_rect.colliderect(rect):
                return True
        return False

    def move(self, direction, delta, walls):
        center = self.center + direction * delta * self.vel
        rect = self.rect.copy()
        rect.center = center
        if not self.collision(rect, walls):
            self.center = center
            self.rect.center = center

    def draw(self, surface):
        surface.fill(self.color, self.rect)