SpiderHeck

There's a lot of luck that goes into this achievement, some maps can be horrible later on, some perks can cause problems and sometimes you just won't get the perks you want for your build, or you will but they'll be on those horrible maps.. And waves are all randomised meaning you can easily get screwed by random spawns or weird bounce mechanics or boxes ect.. That said there's a lot you can do to avoid these bad situations which I'll go through below and I'll put a video at the bottom of this guide of my full successful run.

General Strategy

Early on pick up the perks you need regardless of how bad the map is, from around 30-40 start avoiding the bad maps while still trying to get anything important for your build and wave 50 onwards just focus on picking good maps while hopefully still getting decent perks or at least perks that won't negatively impact your run. I'll go over all the maps later in this guide but generally anything in space or with lots of space is a good bet.

Get some particle blade length early on and always try to spawn kill 1 enemy at the start of each wave, early on it's not a big deal, just makes it go faster but later you'll need this space to create some distance between you and all the other enemies that will be coming at you. Play defensively, let the enemies group up and come to you, and if it gets out of control run away and repeat, stay away from random grenades on the floor (or use them, but be aware this may backfire) and if you have knockback perks some maps will allow you to knock or even lure enemies off the map which is a great way to get rid of the red dual laser flies.

Also, if any weapons spawn that you don't want you can pick them up and throw them away to allow something else to spawn, the Hecksaw, Particle Blade Launcher, Death Ray, Laser Cube and Grenade Launcher were ones I'd regularly throw away.

Perks

Generally anything that increases particle blade size, ammo capacity, slows enemies down or increases drop rates for guns/blades is the way to go, I avoided most movement perks like the plague except for immovable and a run faster one, I found anything more than that would have me losing control too much and end up dying to every random stray enemy or falling off the map, I'll go through each perk and explain why I'd pick or avoid them in the spoiler below:

Maps

Generally anything with lots of space where you can swing around and easily pick up weapons is going to be a good time, anything with lots of bounce pads, boxes or in small, enclosed spaces is going to be a bad time. Later on in your run map choice will become more important than perk choice so keep that in mind, here is my list of the maps going from Best to Worst.



SpiderHeck - Survival Wave 81 - Full Run

This singular RNG hellhole of an achievement takes true mastery of the movement system, aiming skill and quick reactions to things like random flying explosives and rushing enemies (especially the stupidly overpowered Darth Maul wannabee Flies). After nearly 2 solid months of on & off trying, I had to give up on using Particle Blades as much as possible, as the unpredictable and unfair physics (especially when you get increased length) loves to play havoc and cause massive recoil & knockback into other enemies regardless of if you take the perks to reduce both. For the last 10 waves I was on full retreat relying on miniscule Pistol and shotgun spawns, constantly on my last life.

For perks, absolutely avoid anything that affects airborne movement, speed, webs & jumping. Getting flung into the death zone while trying to retreat is the most annoying way to die in the game outside of getting your Particle Blade stuck in the ground with a weapon holding it down. Take both of the Shield perks as soon as you seem them unless they're on horrific maps. Speaking of which, avoid both of the Portal maps (Upside Down & Rocky Loops). They're annoyingly unfair as the AI loves to pop in and out of the portal nearest to you and the weapon spawn points are horrific. I'd also advise against the map Cargo as the crates and no gravity cause constant issues and it's very easy to get trapped. I'd also advise against Dead Weight as the weapon spawns are very poor, and Tribune as there's so little ground to stand on and sometimes the only way to escape is the gravity launcher and you'll just get launched into an enemy that's camping in the path of it.

Don't take any of the explosive+ perks, ever. Random explosions will kill you numerous times and end your run, and most times your shield won't protect you from them as you don't get a window of invincibility when it breaks, while enemies do, which again is why Particle Blades aren't good to stick to as it'll bounce off of them and get you killed half the time. Also avoid the Reduced knockback perk as they stop you being able to use any gravity launchers and the Particle Blade lunge.

Focus on range where you can, preferably getting Recoil and ammo increase early as the Pistol will carry most of the game for you. All of the wheel enemies die in one hit of the pistol while the purple ones take 6 hits from a Blade, and the purple Energy ball flies are an instant kill from a body hit. The small Shotguns are only really useful to use while running for a regular shotgun or pistols.

Now onto the big boys that will save you from so much BS; Enemy Speed reduction, Enemy Knockback increase, Enemy Death Zone fear reduction, and the MVPs, Slowdown on kills and Slowdown on Explosive detonations (and to a lesser extent the Particle Blade impact slowdown). The slowdown perks alone will save you so much pain as you can make a huge opening after just 1 kill and chain kills on the harder to hit enemies during the slow motion. Take Fast Legs early if you don't have other better choices as being able to zoom around the walls and floor is essential for dodging shots.

Now for the BS. This game loves to be highly unfair and enemies will flank you and gang up to block your escape routes and ESPECIALLY will try to kill you through walls or on the corner of anything. All of the enemy weapons can clip through platforms while the Particle Blades can't meaning you're always at a disadvantage. Stay away from boxes where you can as they will also smack them into you and try to get you stuck on them and be wary of Grenades and Mines on the floor as they love to randomly flick them at you completely accidentally. Get rid of the Particle Blade launcher and the Hecksaw where you can, they're only good for the odd kill and can backfire spectacularly. The Laser Beam & the Laser Grenade are high risk but there are places where they can be useful, I used the laser beam quite often on closed wall maps to clear a whole wave quickly and it's very satisfying to clear out 6 shielded dual blade flies in 2 seconds and then immediately killl another 4 of them in the next wave with the next charge. Also, be prepared for Input Lag to get you killed often. It's only a few hundred ms but it's enough to cause you to miss Particle Blade hits, not jump or dodge a hit in time or just fling yourself into the death zone while trying to dodge projectiles.

Other than that, just be patient and try to keep from tilting and raging too hard. When you start approaching wave 50 it's best to slow down and focus on running away while firing instead of approaching enemies.

Good luck.