[PyGame] Particle movement mystery

[XavierPlatinum]

First I would not use a keyword to store variables. _dir over dir.
Second print self.pos, self.dir out during update. Make sure data is right.

Other improvements.

pygame.Vector2 where made for this. Understanding the basic we take care of a lot math. They are always floats.

vector = pygame.Vector2()
vector.from_polar((1, angle))

To give more control over random. Create different list. Then use random choice.

explosion_data = [list(range(1, 30)), list(range(32, 60))]
# in explosion
for particle in explosion_data:
    angle = random.choice(particle)
    vector = pygame.Vector2()
    vector.from_polar((1, angle))

pygame.sprite.Spirte and pygame.sprite.Group can handle your particles. They are a built in framework. They also work faster. I give example later.

For some reason, I thought pygame groups were more resource intensive, I'll certainly change that. The .pos I use is already a pygame vector2, as is vec(), I just imported it as vec for brevity. I also really like the idea of storing the random data as a list rather than calculating it a million times.

I'll implement your suggestions later today and see what I find. Thank you.