Enter this room next, to get ID 3. This is pretty monotonous, isn't it?

And finally get ID 5 from that door! Yay! No more cards to get! But item collection doesn't end here, sadly.

This door leads to a... lighter. Oh... good. Maybe we can burn Big Boss if he gets really, really close to us. Good thing that Zippo's lighter fluid is full and its flints work.

Use your acid-fighting chocolate to enter this door and get... spray! Uh oh. We're not gonna magically improv a weapon are we?

Oh, good! Mrs. Spray! Like Mrs. Pacman, it's pretty much the same thing as the original. Hmmm... flammable. Too bad Big Boss left it in this room, and locked it behind successive doors which could be unlocked with successive keys.

The game makes a good point - too bad you lost your ciga- wait, how the fuck was Snake lighting them before. (By the way, remember in Metal Gear Solid when Snake sneaks in his cigarettes by swallowing them - and says the because of the digestion inhibitors Naomi gave him he could cough them up? Well, I don't. I block out things with a bullshit index over 6.)

Equip the lighter and spray and huzzah! You get a magic flamethrower that glows all different colors! Hooray!

Big Boss is pretty dumb. If you want to beat him, stand on one side of a section of crates and just... well, burn him alive. He is smart enough to occasionally try and go around the crates, but hey, you can too! Way to gruesomely murder your former superior!

Good job, MacGyver! As Big Boss burns to death, he yells out "Snake!" You could be merciful and shoot him with his gun or something, but Snake cruelly lets him burn. To be fair, Boss was kind of a dick to make him collect six different keycards, though.

Big Boss even burns different colors and says "Not Yet!" right before burning up completely and disappearing. It's strange because later games make reference to Big Boss's remains, and this game seems to show that there aren't any left. Oh, whatever.