Metal Slug/YMMV


 * Accidental Innuendo: Some games introduce the option to tone down the Gorn or force on the option for Western markets, by replacing the blood with what's supposed to be sweat. Dirty-minded players may mistake it for a fluid best left unmentioned here.
 * Awesome Art: The amount of detail in the sprites is unprecedented.
 * Breather Boss: Big John in Metal Slug 4.
 * Complacent Gaming Syndrome: Players going for a one-coin run often repeatedly enter and exit of a Slug to take advantage of the invincibly frames given during such actions.
 * Crowning Music of Awesome: In spades.
 * Demonic Spiders: The zombie clones in the final level of Metal Slug 3. They take significantly more damage to kill than the regular clones and the blood vomit attack that was helpful to you when you were able to use it is a nightmare for you to dodge when they use it.
 * Dork Age: The Noise Factory era (who developed 4, 5 and Advance) is the point where opinions were widely split, specifically regarding the games' level design, mechanics, and the reuse of assets from previous games.
 * Ending Fatigue: Metal Slug 3. Mission 5 (of 5) goes on for an insanely long time, and in fact takes up half of the game. It could've been split up into several missions to lessen this trope.
 * Fan-Preferred Couple: Due to the setup of the captured characters and their rescuers in Metal Slug 3 and Metal Slug 6, Marco/Fio and Tarma/Eri are mainly the "go to" couples (although any combination of the four are supported).
 * Fountain of Memes: The announcer, as seen below.
 * Allen O'Neal also counts.
 * Freud Was Right: Take a look at where the Slug Gigant's gun is located at. For added bonus, its shots come out rapidly in a gravity-determined arc, making it look like its pissing.
 * Good Bad Bugs:
 * The AES version of Metal Slug 5 had an un-dummied, incredibly easy-to-access debug menu which allowed to play any part of any stage on demand, plus a bunch of test areas full of free weapons, vehicles, unused stuff and a sprite/animation viewer.
 * Super Cancelling skips the cool-down animations. This is mostly used in Tool-Assisted Speedruns to increase the number of shots per second. However, Leona can use her Moon Slasher multiple times quickly by holding Up and the Special Button and alternating the shoot and grenade buttons. Use this against bosses and you're golden.
 * Growing the Beard: While the first game is still considered fun, it's the second game where the franchise really grew its legs and incorporated many of the Super Sentai-esque hallmarks of the series with the introduction of female player characters like Fio and Eri, more insane weapons and vehicles to use, transformations, and both supernatural and extraterrestrial enemies.
 * High Octane Nightmare Fuel: Some of the concept art for unused concepts are terrifying.
 * Admit it, you jumped a little upon first seeing the character select screen for Metal Slug 2 and 3.
 * The Jimmy Hart Version:
 * The mission 3 music of Metal Slug 2 has a sax solo taken from the shooter Air Duel. The underwater theme of Metal Slug 3 is a remix of the stage 3 music of Air Duel.
 * The Desert theme from Metal Slug 3 bears more than an uncanny resemblance to Iron Maiden's Powerslave.
 * Memetic Mutation:
 * RAWKET LAWNCHAIR!
 * SHAWTGUHN!
 * HEVEE MASHEEEN GUHN!
 * MISHOWN COMEPLEET *ending theme*
 * Moe:
 * The amount of blood spilled, flesh torn and bones crushed is usually proportional to the cuteness of your mech.
 * There's also Fio, the series' resident Moe character.
 * Most Wonderful Sound:
 * "You're great!" gained from racking up a ton of points at the end of a level from rescuing a ton of POWs without dying and possibly clearing the mission with a Slug still intact.
 * "Mission Complete!" followed by the Mission Complete theme.
 * Replacement Scrappy:
 * Trevor and Nadia, as they replaced series' regulars Tarma and Eri in Metal Slug 4. The latter two actually appear in order to justify stage transitions (they're driving the vehicles that pick you up at the end of every level), but that's just not enough.
 * The announcer of XX is considered to be unimpressive compared to the previous ones.
 * Scrappy Mechanic:
 * Metal Slug 5 introduced a Mega Man-like slide move. Though it was useful at times, the problem with it was that it was activated by holding down and pressing jump. So most of the time when you wanted to jump and shoot downwards (a common tactic to shoot things underneath you), you would slide instead, and probably die, or at least waste time. Thankfully, it was taken out of future installments. However, once Damn You, Muscle Memory! is overcome, the slide is an absolute blessing.
 * The "Metallish" combo system (where medals are given by shooting enemies and a fever time appears when collecting a special emblem) in Metal Slug 4 is regarded as very confusing. Not all of the time the player will earn medals, and the combo fever stops when a player goes into a Slug. It was revamped to a simpler combo system in 6 (where shooting enough enemies/obstacles will increase the score multiplier until coins spew out for a short time) and has retained since then.
 * Special Effect Failure:
 * The player character is mostly composed of two separate sprites (the upper and lower bodies) to make the action more fluid. Occasionally, the two sprites merge when jumping, making the character really squat.
 * The Evil Spirit Incarnate's wings detach from its body when it readies its scythe.
 * That One Boss:
 * Allen O'Neal from Metal Slug and Metal Slug 2/X. Yeah, this guy is extremely hard to defeat if you don't know how to predict his attacks. He can shot with his Machine Gun and if you try to move to the other side he just use a grenade towards you!
 * Sol Dae Rokker from Metal Slug 3. Its only weak point is the small red jewel in its forehead and due to the boss moving constantly it can be quite difficult to shoot. The boss also levitates way above the player, meaning that you can't harm it with grenades. Most of its attacks aren't a big deal, but That One Attack where it spreads a flurry of yellow beams in random patterns is a nightmare to dodge, specially after the boss is enraged.
 * The Sandmarine from Metal Slug 5. While most of its attacks are easy to avoid, when it submerges/emerges it will fire a bomb volley and make hell literally rain upon you. You need extremely good reflexes to avoid the bomb spam and don't get cornered by this monster.
 * The bosses of stages 3 and 4 of Metal Slug 6 are MUCH more durable and nasty than the first two bosses were. Both take ridiculous amounts of punishment and have nigh-unavoidable attacks. Expect to use a lot of credits.
 * The stage 3 boss deserves even more special mention. Firstly: You're moving to your right, constantly, which means it feels awkward reaching around and shooting at the robot, NOT TO MENTION THE CONTROLS AUTOMATICALLY FACE YOU TO THE RIGHT IF YOU TRY TO JUMP TO THE RIGHT TO DODGE SOMETHING. This means it WILL take forever to kill it. Secondly: IT KEEPS ATTACKING, ALMOST NON-STOP. And all of them are constant, even with the obvious pattern, so you'll be killed repeatedly. The "vulcan fix" skill is very useful here (hold down the shooting button to keep shooting in a fixed direction). Also, don't even try to take your time in defeating it, or it WILL GET PISSED and keep swinging his electrified arms reducing the safe zone to a ridiculous minimum!
 * Crablops round two in Metal Slug XX. While 7 was kind enough to lend you a Slug Armor to fight the boss, in XX, it was changed to a Slugnoid - the only Slug that undergoes literal battle damage and more than likely will end up useless after a few seconds of battle, forcing you to fight Crablops stark naked. With the head spamming fireballs, plasma beams and restricting your movement with rocks, and the legs decreasing your maneuverable space by lauching bombs and acid worms, prepare for a hard battle. And that's not even taking into account when you get to the lift and Crablops Turns Red.
 * SNK Boss: You can count the final boss in Metal Slug 3D as a Final-Exam Boss because there are no powerups to collect, and you need fully-loaded weapons in order to defeat it.
 * Tough Act to Follow: Metal Slug 3 is often deemed as the best in the series and was the last game developed before SNK went bankrupt in 2000. The sequels since have been often compared unfavorably to it (even those created by SNK since their resurrection), especially 4 for recycling previous assets.
 * Ugly Cute: The Mars People. They're adorable, in a weird sorta way.