Neon Chrome

There are a total of 75 unlockables in the game, and the amount you have can be tracked on the giant screen on the right of your chair in the hub. Here, unlockables are weapons, abilities, and enhancements. You can see specifically which ones you have and don't have by going to the top of the hub to the crates for each and scrolling through what's available. Red items are ones that you haven't gotten from the blue gear towers, and if you hover over them, it'll tell you which Floor's levels you can find them in. Like with special levels that don't repeat, the blue gear towers will never repeat and will always give you something new until you've gotten all gear from that Floor's levels. This gear is all straightforward and just requires you to replay levels and open more blue gear towers to get more gear on that floor. The special levels via purple elevators are best for this, because each one is guaranteed to have a blue gear tower to open. Regular levels just have a random chance to contain a gear tower.

Beyond those normal gear chests, there are eight hidden gold gear chests with eight hidden items. These are represented by the question marks in the gear chests in the hub. Each one is found in a specific special level accessed via purple elevator. Because they are found in specific special levels, take note of my important bit in the roadmap about avoiding RNG. To sum it up here, get the hidden golden chests in each special level when you reach it for the first time, because if you don't, you'll have to first complete all special levels on that floor, then access more over and over while you wait for RNG to give you the special level you need. This is very tedious and could add hours to your completion time. To avoid this, use the below guide to look out for the following special levels. This is repeated from the roadmap. Below the points are how to find the hidden collectible in each special level.
 

• Floor 1 - Fireworks (Laser Pistol) *ROCKET LAUNCHER or ROCKET ability REQUIRED!*
• Floor 2 - Locked Out (Gauss Gun)
• Floor 2 - Triple Towers (Piercing Pulse)
• Floor 3 - Exordium Imports Inc (Antioch Grenades) *GRENADE ability REQUIRED!*
• Floor 3 - Hovertank Boss Fight (Blowtorch)
• Floor 4 - Welcome Back? (Heavy Rifle)
• Floor 4 - Communter District (Duramax Wall Smasher) *ROCKET LAUNCHER or ROCKET ability REQUIRED!*
• Floor 5 - Emergency Accomodation (C4)

To address those bolded notes first, as you can see, there are three instances where you need specific gear to access the gold chest. Personally, once I unlocked Rockets ability, I would buy it for every run anyway, and I recommend doing the same, just to be safe. If you do get one of those three special levels that requires specific gear and you don't have the gear, DO NOT complete the special level. Save and Exit, and go through the purple elevator again to get a different special level. This will "save" the special level for later and will keep it in rotation, avoiding the need to wait for RNG at the end.

Here's a description of how to get the hidden chests in each of those special levels above.
 

• Floor 1 - Fireworks (Laser Pistol) *ROCKET LAUNCHER or ROCKET ability REQUIRED!*
  • This one is a pain. If you go to the green elevator but don't leave, you'll be able to see an orange destructible tower up top off the screen in a place you can't reach. What you need to do is head to the catwalk off to the left and shoot up into that area with a rocket (either a launcher or the ability) so that the blast destroys the tower. The pain is that you're shooting at something offscreen, so you have to just hope you've got the right angle to hit it. I found it best to aim a little "low" (i.e. down to the right more) so you can actually see your rocket exploding on the wall just off screen, and from there make tiny adjustments "up" little by little until you break the tower. That'll open up the purple door off to the right so you can access the gold chest
• Floor 2 - Locked Out (Gauss Gun)
  • Right at the start of this special level, there is a button that opens the purple door on the left with a timer. Don't go through it or use the button. Instead, go straight up and you'll see what looks like an uninteractable door on the wall up top. You can actually destroy this "door." Do so and go up to find this chest
• Floor 2 - Triple Towers (Piercing Pulse)
  • On the left side of this special level are tons of units where enemies spawn from. Go into that room (which is accessed via the blue key in the top room) and destroy all of those units. That'll open the purple door on the right side above where you entered, so you can reach the chest
• Floor 3 - Exordium Imports Inc (Antioch Grenades) *GRENADE ability REQUIRED!*
  • Right in the center of this level is a crate with a interact symbol inside it. Use grenades to destroy this crate to reach the button under it. For some reason, grenades definitely work (I used them) but there are reports that rockets don't. Once you destroy the crate and press the button, this opens a door on the far right bottom corner to the chest
• Floor 3 - Hovertank Boss Fight (Blowtorch)
  • This gold chest is easily visible but is only accessed by using the white key that the Spiderbot boss drops at the end of Floor 1. So, you'll need to play starting from the beginning of a run, defeat the Spiderbot boss, grab the white key it drops, then play through your run up to the Hovertank boss at the end of Floor 3, destroy it, then use your white key to open the obvious door by the elevator with this gold chest inside
• Floor 4 - Welcome Back? (Heavy Rifle)
  • In this special level is a little training course where you need to run through and shoot the dummies and get to the end before time runs out. It's extremely lenient and you'll easily do it first try. Doing so successfully opens the door to this gold chest. As a side note, I got this during the tutorial of the game, and hopefully you do too, because this is the best weapon in the game by far
• Floor 4 - Communter District (Duramax Wall Smasher) *ROCKET LAUNCHER or ROCKET ability REQUIRED!*
  • ​​​​​​​This is another case of shooting a rocket off screen, like the Fireworks gold chest above, and is equally annoying. If you go to the northeast corner of this special level, you'll be able to see the orange destructible tower off to the right. You barely have any room to squeeze a rocket in there. You need to go up to the upmost point on the balcony and shoot east-southeast so your rocket hits the corner of the wall opening to destroy everything. Again, this is offscreen, so you have to just make minor adjustments. I recommend firing 2-3 rockets with minor adjustments, then go check and see if the door is open, and if not, come back and try a few more. Once you hit it, you'll open the purple door to reach the gold chest
• Floor 5 - Emergency Accomodation (C4)
  • You'll first need to get the blue key, which is off to the right side past a bunch of enemies. Once you have it, head northwest to the green elevator and you'll see the blue door to use the key. Do so, and now you can press the button near the elevator. This opens a door back where the blue key was, giving you access to two orange destructible towers. Destroy them, and this opens a purple door by where you first started this level. Go through to find the final gold chest