What exactly has to be done to get the weapon for which you need to find 4 secrets in one level?
I've had two consecutive runs where I managed to find 4 secrets in the same level (once in the Foundry, once in the Gearworks), but I didn't get the new gun.
Is there a specific requirement not listed?

I've tried looking for an answer on the official site as well as the Steam forum, but I didn't see this problem mentioned, so I presume it is not a bug.

Should unlock when you find 4 secrets on one level during one run.... that should be all

The best perk to achieve this, in my opinion, is Fireforce.

Thanks, then it *is* bugged, as I did have the 4 secrets in one run, in one level.
As for the best perk to go secret-hunting, Bluegrass works for me better, as a) it enables to reach areas higher up, b) saves you from fall damage if you time your jumps well (good for secrets reachable with a fall), and c) lets you cross sections of lava while taking minimal damage )only touching the surface once).

Bluegrass is a good one for mobility, yes, and for generally finding secrets in most levels - but there is just so many secrets in Gearworks under, behind and across lava... several of the rooms there have 3 and 4 secrets covered in some form other by lava.

I finally managed to get that gun - turns out I actually needed to find 5, not 4 secrets.

good, at least you will get all guns :)

Fireforce is the perk I play with damn near all the time, it's simply too useful for me to consider much of anything else -though I do welcome the diversity and challenge that others offer. With that said, I've had the fortune to snag upwards of at least 18 and at most 20 badges in one run (not stage) before, however I've not found but 3 secrets in one stage. Whether this owes more to my particular style of play, luck in badge drops to help aid discovering secrets or both is beyond me, but that badge run told me that no small amount of luck is going to be necessary if I'm going to have the stuff necessary to really go hunting.

For my part, I'll be leaving this for an attempt at 'Endless Mode'.

Right now I've been playing around with different combinations of weaponry and mods as I come across them. (Currently 2/12 with 2 of those 12 being to the Maw and 1 of them being the Gumball Machine and I taking each other out at the same time). I've found that when it comes to weaponry I really am not a fan of the 'bubble gun', though I respect the damage it can do, and when it comes to mods I have no use for 'Spread', 'Seek' and 'Mine'. Mines are too tragic when encountering the boss pair that look like iron Pac-Men, Spread makes it remarkably difficult to hit the Gumball Machine's light (especially with my favourite gun, Egon's Pride) and Seek just does not work when it comes to the Gumball Machine. If there was the option to completely jettison a mod at any point in time during play I'd be set but, as it stands, those mods I see, say 'no sir, good day' and keep on my way.

Fireforce + Egon's Pride/Consolation Gun/Pizza Launcher is just my favourite way to play. Save for my last run with the Mine mod, I've found between 2 and 5 Extra Jump badges and that really is a life saver. Relying on luck, as it were, to help with finding the badges seems to me to be the way to go when trying to both complete the run and unlock the gun at the same time.

For finding secrets, look everywhere. Some of them are hidden behind passable (for lack of a better term) walls; these are fairly easy to find by simply shooting at the walls and looking for the spots where your ammo doesn't collide. Others are 'hidden in plain sight', as it were, being cleverly disguised with the graphic textures so you may not notice that there is a little alcove just around that corner right over there. Hopefully this isn't a spoiler but note that, with Fireforce, there is some lava swimming you can do that will lead you to at least four secrets (one of them an "uber" secret). There other hint is to look up, and do so from different angles. In the Foundry in particular, at least one room has three secrets that are easy to get to but aren't obvious to find unless you take some time to wander around a bit. You can get to them without Fireforce but make sure you have full health before doing so.

You're right, though, some of them you will not normally be able to get to without certain badges or specials, like the ramp or, umm, I think it's called the togatrooper - the wings that let you fly for ten seconds or so. Endless Mode sorta solves that, and the cake level can also take care of that problem once in a blue moon.

For perks, I really like Luck. This one increases the chances of badges appearing, so you'll have more opportunities to gain multiple jumps and increased jump height. Be careful taking too many jump height badges. They're great for finding secrets but you can get yourself in trouble fairly easily with three or four height boosts. Pretty fun, though.

Speaking of which, having that ability to jump high and long makes the Sanctum boss, and also The Maw, pretty easy to defeat. Just keep yourself in the air as much as possible - especially for the Sanctum boss - and they'll go down much faster since you'll have to worry less about survival and can concentrate on putting shots on target.

For Endless mode, you have a pretty cool weapon to unlock: slower rate-of-fire but very high damage from the get-go. Note that you do not need to go to The Maw in Endless mode - it'll wrap around back to the foyer if you choose to take the normal teleporter after the Sanctum boss.

Oh yeah... spoiler coming up but I think it has been posted in another thread:
















There are at least two guns that you can use to boost your jump height, using their recoil once you're in the air for a pseudo-flying ability. Not super-easy to control, but it does work. This can help you access some of those secret areas located above you.

This not-quite-a-cheat (you don't enter a cheat code, nor open a console) might make it easier to find a few of the secrets:

F4 strips away the 'skin' of the rooms and bots, leaving just the polygons for those objects. Looks pretty cool to see the game that way. Pressing it again restores the skins, and also restores them if you accidentally press F5 (different graphic change that makes it all-but-unplayable).

Instead of replying to your post above I'll replay here.

I stumbled across unlocked the Kegerator this morning along with 20 badges. It was a damn nice run. Playing the the Kegerator, unfortunately, is anything but nice. It isn't that it's more a short-range weapon, the arc will take some time to learn or that the mines damage the player, rather it's that the gun is bugged.

Enemies have a very noticeable grace period where they can enter a purple mine bubble and not set it off. I've also observed no damage taken from the mine blast at levels 3 and up. This grace period isn't simply for enemies that happen to be in the area of the bubble's formation when the round is fired but enemies passing right through, something that does not happen for the player when passing through purple mine bubbles fired by enemies.

This is frustrating, as the gun seems like it could be very interesting and no doubt challenging to play with. As it stands now, I can't see a reason to use the thing.

I only tried that weapon once, and not for very long. Is it even usable against the airborne robots?

It's very usable, the arc just takes a good bit of practise and the same with anticipating where the small ones are going to move. The damage of the round itself is good, the real problem with the weapon is that its secondary function (the mine) truly seems to be bugged. I came to notice this when using ramps and a height advantage to lay a path of 'fuck you, leave me alone robots' as I walked back up the ramp and saw them often pass harmlessly through the purple bubble and not set it off, while at other times they didn't take damage they should have due to the range of the blast. In the latter situation some robots at/near the same spot took damage while others didn't.

If this gets fixed the gun will be a really challenging gun to use but, unfortunately, I can't see myself using it until this is fixed....and I definitely can't see myself going after The Maw again until the issue with enemy fire passing through curved surfaces is fixed.

With that said, the crossbow is quite challenging to use when it comes to the small floating mines, ground mines and fast-moving, upright aerial cannons that move like they're hopped up on something illicit. The bolt fires very fast but those enemies (not the mines) move quickly and erratically, something that is honestly fantastic. When it comes to the bigger enemies the crossbow simply shatters them but those small buggers provide a special challenge. The various weapons in this game are among the most interesting and functional I've seen since Unreal.

...now if only the damned Kegerator worked! XD