You're supposed to sneak past the Security Carts.  The gold carts were made painfully tough to encourage waiting and slowly making your way through the level.

     Though me thinks the mega or Omega shooter can kill them fairly quickly if you want to grind for them.  Key word is think here. 

     Honestly sneaking through the level becomes easier in farther playthroughs once you have the reverse hook.  Much faster to run on height zero where there are no security cards in the first half of the level to just climb up and hit switches before going back down.   Also reverse hook is needed for one hidden weapon there, but have fun getting it to appear.

I am in Level 21.3, so, I guess, I am pretty Close to the end of the game. My question is, where can I find the items, that I Need to craft stuff in the shop in stage 16? I mean, I collected some stuff in the end of an earlier stage. But where can I get the rest?

@the player, it depends what you're looking for. Some stuff doesn't show up until you've past a certain mode. Anything with clear metal refers to the mode you have to pass to get it. I spent ages trying to find the clear metal super wolf lol. Some stuff you can get by finding the secret landing on 18-3, changing the dial to 4, then going back to 18-2, finding the secret landing, and waiting for all the stuff to fall. I think changing the dial changes what falls, but I don't know which numbers do what. Also I think the sound the objects make as they fall changes from a thud to a bloop when nothing new is going to fall.
My advice would be to stand still til the bloop tells you everything's fallen, then check your objects list to see what's there. If you just run around picking everything up, you'll have to check your collection items, and that's a friggin nightmare.

@player... not sure where you get those things to be honest. Haven't done a lot of crafting. At the moment I'm happy with the spirit sword and a super yoyo for long range. Hoping to replace the yoyo with a water master when I beat super wolf mode, and an ultra yoyo probably after beating extreme, though not sure when the chaos flare shows up.

@mahmood... that will be a number puzzle. I can't remember off the top of my head which one is in 23-1-A, but I think it's 16384. If not it will be 210.

@jesseleivo... if you use the camera to explore the platform that the key is on, you should find it can't be hooked onto apart from a bit right at the far end. You need to smash all the stones to get to this hookable bit. It's something like the second to last square from the right.

Hi
is there any way to play this game in English with Jaws for Windows? I think dictionary files may be useful for it.

Mahdi. When you hear the first message, it's your character asking about how to land. At this point slow your speed right down to 1, and your altitude down to 1. Then you need to press l to find a landing. You'll start hearing a beep coming from the right. As it sounds in the center of your hearing, press down to land. If you go past, you can press shift l to turn around, and shift r to turn back again. If you mistime it you'll crash and have to try again.

@flame_elchemist Turn the dial in 18-3 to 3 and the minigun will be in 19-1

I don't know what the switch on the right does on 25-1, but you don't need it to get past that screen. I don't know if it's just a trap or if it does something useful.
What you need to do is hit the switch on the left, then go down to the door at platform 100. Kill all the stamina bots, but careful not to destroy the metal box. Get the piece from the box, then go back and hook up to 200. Go in the door, use the piece on the keyhole, then do the same, kill everything, without destroying the box, then get the piece and take the lift all the way down to 0 and exit via the door. Also if you don't have the lift sensor, you should first go up to the door at the very top on the left. Destroy the jet, but be careful not to destroy the lift sensor left behind. You don't need the sensor but it's useful for letting you know when the lift is coming, and for when you're on the lift approaching a platform.

can anyone tell me what should i do in 24 level 3?

@player, it's the same as an earlier level: power.
@mahmood
You were given a piece of paper by I think a mud killer, it has the number 35980 written on it. You have to kill those spark boxes one at a time then set the dials to match that number, but you have to start at the bottom, so the numbers go in reverse, 08953. To get to the bottom, drop off the platform, then keep checking your coordinates as you fall. Even though you're in empty air, you can still use your hook. You need to time it so you fire the hook and it connects before you hit the ground, but so that you end up dangling near enough to the ground not to die when you arrow off the hook. You can hook back up to each platform after setting each dial. There might be another way to do this, but that's how I did it before I got the UFO.