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The BFG9000. Without a doubt the most powerful weapon in classic Doom. Being capable of killing

big groups of demons with ease and even take down a Cyberdemon in 2 shots.

But it's a pretty complicated and often misunderstood weapon. Is it a glorified rocket launcher?

What's with the green sparkly things that appear? Why did this Cyberdemon survive 10

BFG shots while the other ones dies in 2?

How the heck does it work? Let's find out.

Well, the BFG shoots huge plasma balls of pure, concentrated death. What not many people

know is that the projectile deals the least damage of the entire package. A BFG ball deals

random damage between 100 and 800 in multiples of 100.

So, where's the rest of the damage? The majority of the damage is dealt through the green sparkly

particles, but how exactly do they appear?

To explain that let's take a step back. Let's take a thorough look to what happens when

you pull the BFG's trigger. First of all there's a slight delay before firing the gun. You

can hear a stock sound effect of electricity charging up.

And behold, there is our BFG ball.

The BFG ball keeps traveling until it hits a solid

surface like a wall or demon.

Something peculiar happens when the BFG ball explodes. On its third explosion frame it

will activate its secondary attack. In Doom's code this is called a BFG spray. Put on your

turbo nerd goggles, because were gonna walk through the code.

An angle is calculated based on the projectile's trajectory, which is 90 degrees in our example,

minus 45 degrees, plus an addition based on the current iteration. The first iteration

is zero, so the calculated angle will be 47.25 degrees.

Then an invisible tracer is shot that originates from the player who shot the BFG ball. The

angle of this tracer is the one we just calculated. The game checks if this tracer hits an enemy,

if it does, spawn the green particle effect and deal damage.

The damage calculation is unorthodox to say the least. A damage value of 0 is initialised,

then a random number between 0 and 255 is picked from the RNG table, and a bitwise AND

is applied. Simplified: this bit of code will generate a number between 0 and 7. Then a

1 is added, so a random value between 1 and 8 is added to the damage.

A random value will be added to the damage 15 times. Because of Doom's static and predictable

RNG table the calculated damage is always between 49 and 87. Now whoever is hit by the

tracer must receive the calculated damage. This tracer code is iterated 40 times, with

the tracer angle slightly changing each iteration -- creating a cone of tracers.

So to keep it simple: your BFG projectile explodes, and you emit 40 invisible tracers

in the shape of a cone in the direction the BFG ball was shot that each deal random damage.

These tracers, like pistol and chaingun tracers, are affected by vertical aim. This means it

will also hit enemies above and below you as long as you're not too far away.

Time for some pro strats. To deal maximum damage you need to ensure all 40 tracers hit

the opponents, so for instance, if you want to hit this Cyberdemon with 40 tracers you

gotta get close to him. A risky, but rewarding move as it allows you to take out his chiseled

bum with only 80 cells.

Another strategy is to not bother with the BFG's projectile at all. You can take out

big groups of demons with ease, but often you want to do that fast. To not wait for

the BFG ball's travel time, shoot against a wall and then peek around the corner the

moment you emit the BFG tracers.

If you time it really well you can kill monsters behind your back. Even if you don't face your

enemies, you can still emit tracers from whatever direction. Very sneaky.

And speaking of sneaky. In deathmatch you can actually shoot the BFG without making

a sound. While you charge your BFG, quickly hump the wall so the player does the "unf"

sound. This sound overrides any sound your weapon is making, and that's how you can abuse

the silent BFG trick.

And that's how the BFG works. There's many, many strategies for this gun, and it's up

to the player to be creative. Definitely one of the most unique and strategic weapons ever

made. And probably by accident too, since the gun was supposed to shoot 40 projectiles

instead, but that was too laggy and according to John Romero it "looked like Christmas",

so they used a hitscan spray attack instead.

So in the end the cover of The Lost Episodes of Doom is kinda accurate. The drawing just

depicts a BFG tracer hitting the baron, but visibile.

And the same with the Doom comic. Many people say the BFG is depicted incorrectly here.

In the comic it looks like the BFG's unleashing a crapton of bullets, but actually it's the

BFG tracers. Those comic artists knew their stuff, let me tell you.

Thanks for watching, hope you learned a new thing or 2. Also a big thanks to my patrons

and a very, very big thank you to:

Andrii Dykhlin CIPRIAN RUSEN

Sean Hwang Roman Orekhov

Turbine2k5 Steven Bohn

Joseph Kullmann

Thank you for the support this month, I really appreciate it. See you in the next video!

The Description of How the BFG9000 Works