YMMV / Sidewinder

• Breather Level: Shining Wings, the last mission of Lethal Skies / Sidewinder F. It's a simple mission that involves destroying a megafloat and nothing more, almost as an apology for Hopeless.
• Demonic Spiders: The Delta VTLs in Lethal Skies 2. They're ungodly tough, love to spam missiles, and can easily perforate you with gunfire if you get close. And while they don't look very aerodynamic, they are nimble enough to dodge missiles. Fortunately, they only appear in three missions, two of which are optional.
• Game-Breaker: The Viper and Tarantula missiles. They're multi-warhead and multi-lock weapons that can do a lot of damage or even One-Hit Kill targets depending on how spread out the locks are. The Tarantula missiles are especially broken because they make ground attacks quicker.
• Nightmare Fuel: The "Summary" track from the second game, played in-between the chapters as the bad guys' next steps are detailed by the narration, is pretty eerie.
• Player Punch: Players who went through the first Lethal Skies get one in Mission 6 of Lethal Skies 2. It brings back Jake, your Lancer from the former... as an enemy.
• That One Boss: The huge helicopter and the Spider Tank in Lethal Skies / Sidewinder F. Both are very difficult to destroy in their own way; the former moving around a lot and spamming missiles, while the latter requires you to destroy parts in a certain order and the core being vulnerable from behind. Said core requires that you get very low to the ground to destroy. Hope you have the multi-warhead missiles equipped, you'll need them.
  • The Spider Tank makes its glorious return in Lethal Skies 2, this time with its vulnerable core located underneath the machine, again forcing you to skim the ground for a clear shot. It's also a Time-Limit Boss where you have to destroy three of them before they level an allied base. At least this time you don't have to destroy any other parts.
  • The supercarrier in the penultimate mission of Lethal Skies 2. You have to sequentially take out a number of weak points that can often only be attacked from one side, all while it's constantly spraying you down with flak and missiles. It's also sheltered on all sides, forcing you to come in at very specific angles. And you have to listen to the enemy commander gloating at you every time you restart.
• That One Level: Lethal Skies / Sidewinder F have a few:
  • Death City, which requires you to destroy a ground based carrier before it launches a Super Prototype plane, is hard in the sense that the unit has to be destroyed in a certain time limit while dealing with missile spam. Not to mention that the treads have to be destroyed and they're low to the ground.
  • Hopeless, the second to last mission. To elaborate, you have to defend your base from Tiger helicopters and a Spider Tank that's attacking it. Taking down the Spider Tank is difficult enough, but once it's destroyed, a huge helicopter comes in with another Spider Tank in tow. Now you have to focus your efforts on destroying both the Spider Tank and the large helicopter, and you're more than likely out of missiles and have to resort to using your guns to take these things out. Befittingly, the subtitle of this mission is In The Face of Death.
  • Babel, the mission where you have to disable a radar jamming site while being targeted by missiles constantly. A plane with a high chaff and flare count is a must.
  • Lethal Skies 2 has a few frustrating ones as well.
    • Mission 7, Escape from Azhad. It's straight-forward enough, except for the last part: you have to make a vertical landing inside a courtyard. The game forces you to use the AV-8B to avoid the level being unwinnable, but the game doesn't tell you how to make a vertical landing. You'll have to resort to trial-and-error to figure out how to activate the AV-8's VTOL or run out of fuel trying.
    • Mission 13, Rush, is where the game's difficulty curve becomes a sheer cliff. Not only do you have to fend off both enemy ships and a squadron of enemy planes (forcing you to grab both anti-air and anti-ground weaponry and thus cutting down your effectiveness at specifically dealing with either), but after you're done with most of the existing enemies, Gyrfalcon shows up and takes off the kid gloves, coming at you with an X-29Z that has a truckload of health. Never mind running out of missiles, it's possible to run out of fuel trying to shoot the guy down because of how ungodly long this mission takes.
    • Mission 14, Road to Victory. You start out having to escort a ground convoy past a bunch of armored walkers that'll eat them for breakfast if you're not fast enough and can easily withstand anything short of a Tarantula. Unless you brought a ton of ordinance, you'll be down at the first hurdle. The last part of the mission is no joke either: you have to destroy the enemy fortress by flying inside and then shooting out the vital areas with your gun. There's very little room to maneuver inside the fort, and it takes incredible precision to take aim at each target in turn without crashing into anything.
• They Wasted a Perfectly Good Character: Gyrfalcon 1 aka Jack Russell is the first and only recurring enemy ace in the series, and has the "honor" of standing out as the only character to do a Face–Heel Turn. Though he is built up as a threat and implicitly a Well-Intentioned Extremist, what exactly forced him to become one isn't revealed, he only appears in a handful of levels and goes down without much fanfare. Moreover, if you haven't played the first Lethal Skies title or don't bring Grace along on the missions where he's encountered, you may never even discover his true identity beyond "an FN ace who turned evil".