Hard 1 - Dual dip
Start with collecting the stuff in your starting area. You can use 2 bombs in here. One will be needed to get to the invincible and bomb while the other can be used to either make the bottom left corner easier or blow the orange security mine up.
Once you have everything get the invincible. Use this to blow the security mine up if you didn't before. Now go through the arrow and collect the auto-jewels. The invincible will sort out your oxygen. Now you need to plant a bomb at the top to get to the orbs. After this use your other 3 bombs to get to the 4 bombs but don't blow any jewels up. Once use these bombs to get the remaining jewels and key. You now have all you need to exit.
Hard 2 - Key cloning
Your goal is to get the white key through the inverter and triplicator. Since the key isn't in line with the inverter and can't be pushed, you need to use the rocks. Push 3 rocks so that the key will topple off of them to the right, start with the bottom of the 3 rocks and work up. Now make path around the triplicator and inverter, then create path to get the key to topple.
With your 3 rainbow keys you can collect the 3 orbs needed to get to the jewels.
Hard 3 - Lethal laser
You need to switch all 4 switches on to get to the key. This needs to be done in a certain order to prevent setting the C4 off. This is the order to switch them on: Yellow, blue, red, green. After getting the key, the rest is simple.
Hard 4 - Fiend garden
If your quick at the beginning you can use the rock near you to kill the nearby jewel monster straight away. Go around collecting the loose jewels until you have enough to pass through a jewel door and collect a shield from the top left corner area. With a shield you can walk into a jewel monster and the jewels should be enough to open up another shield. Better still if you can kill a monster near the shields and destroy the walls around them meaning you don't have to use the door. While shields are enough to get through this level, you can still push rocks to kill them of course.
Hard 5 - Flare star
Press either of the return points and start traveling up to the super jewel. Don't go all the way as you won't make it. Allow the heaters to kill you so that your explosion doesn't destroy the jewel. When you return you can now get this jewel with some of the heaters now gone.
Deposit this jewel, step onto the other return point, then go to the right. Again the heaters will kill you, but after returning, the missing heaters means you can make it across.
Go up and collect the normal jewels and press the water switch. The heater underwater can't burn you now. Go underwater and collect the speed pill and surface as soon as you can. While out of the water, get the jewel at the top right area, your speed means you can get across the heated spaces. Cool down fully before going back over them again. Now go in the water and collect the 2 cups. You don't have any time for mistakes here or for your speed pill to wear off.
After getting some air, make your way to center where you started and get the cup at the bottom. After depositing these go to the far left. Use the invincible to firstly get the super jewel at the top followed by the underwater super jewels. Finally you can deposit these and exit.
Hard 6 - Directions
Firstly take the right rock down past the walls on the right and push hit through the inverter on the bottom row. This gives you 3 jewels after the triplicator. Now do a mirrowed copy of that with the left rock; push it left a bit to drop it past 3 layers of walls and be ready to push it through the filter at the bottom. Press the second to bottom depth switch first so that the water monster moves and you can get 9 auto-jewels from it.
For the weak rock at the top, firstly press the second to top depth switch and drop the weak rock through the lined up inverters. It will end up as a weak rock again. The water is there so it doesn't break. Now reduce the water 1 level and push the weak rock through the nearby filter. Now press the bottom depth switch (its on the left side) and push the weak rock through the inverter. This will turn to an explosive rock and since there's no water, blow the wall up to the keys.
Using the water switches again, guide the last explosive rock to the bottom without it blowing/breaking. Drop it through the filter, then the 2 inverters on the next 2 levels and lastly the filter above the remaining fish. The water level at this point doesn't matter.
Hard 7 - Century coin
An easier level compared to most others in here. While the power-ups are nice, they're not essential so don't take risks getting the keys. There's a return point to the upper right area you can use incase you get killed. Don't let any jewels get destroyed, there's no spare in here, so be cautious with where you're dropping the explosive rocks.
Hard 8 - Great wall
Plant the first bomb to get to the room below without harming the C4. Place the bomb in the next room into the bottom right corner to open up 2 more rooms. In the room to the right, use the bomb 1 space up from the bottom right again, opening up another 2 rooms. Now use a bomb in the bottom right corner of the lower room, to get to a further room with a bomb in and a room with jewels. Finally place the last bomb where the 2 far right rooms meet so you open them both up.
Hard 9 - Blocker
You need to use the pushable strong wall to block the red laser, but this can cause the yellow laser to activate and trigger the C4. Push the wall up so its in line with the yellow laser boxes and C4, then push it to the right into the red laser path. The red and yellow laser will both be blocked.
In the next area, drop the anvil so its next to the green laser box. Now you can switch yellow off without the green laser triggering the C4. Now the jewels and exit are available to you.
Hard 10 - Aerodynamics
You are enclosed in a constantly falling barrage of rocks. Get the speed pills so you can move faster and cautiously collect the key and orbs (don't get the auto-jewels yet). Once you have them, move to the far right and then down, you will pass a door and then a clock. With time stopped, you can collect the jewels without the worry of the rocks reaching the C4 at the bottom.
Hard 11 - Collector massive
A big level with plenty of spare jewels. There's no specific order to this but this is the order that I use. Start with the 2 break jewel limits and head into the below room to collect the keys, orbs and bombs. Now go back to the above room and then the one to the left. Set empty space under the triplicator and room for the jewels to topple. Now let the rocks drop in. Collecting jewels from the bottom will free up more room for triplication. Now go into the room below this and straight to the room on the right of this.
Get the mouth monster to eat the bomb x 2 and guide it into a mine. You now have quite a lot of bombs. Back in the room on the left, you can go to the central area, using bombs to take care of the growing walls. After blowing the 2 teleporters up, get the shields and invincible. Now head to the room on the left and walk into the slow homing monsters. Also kill the jewel monsters in the room above while your here. Once you've got these jewels you should have enough to exit (bear in mind there's lots of auto-jewels around the exit). Just step into the teleporter in the top center room.
Hard 12 - Excavation
Push the gunner against the third to top wall. After it shoots the wall leave it there until it takes the monster out too. Try not to let too many jewels get shot while you collect them. Now you can use the gunner to blast your way to the far right area. Collect the break jewel limit, but leave the cups for now. Now push the pushable strong wall to the bottom and into the next room. Push this wall across into the spring. It will stop between the laser boxes so you can now switch green on without blowing the level up. Now you can get the cups and exit.
Hard 13 - Time field
You have 30 seconds before the time bomb blows the C4 up. Collect the jewels around the edges while keeping careful watch on when the bombs in your path will blow up. This level is more down to your reflexes than anything else.
Hard 14 - Central lock
Firstly guide the jewel monster to the security mine below it. Now do the same again in the room below you can now get to. Now go back up and pass through the arrow (make sure you have a shield). Use your shield the kill the monster, but make sure its against the security wall, blowing it up and allowing the rocks above to be dropped to the room below. Now use the rocks to destroy the remaining security mines.
Hard 15 - Diamond pool
Firstly go right, don't disturb the rocks above or below you or you will regret it later. On the right hand side, press the lower of the depth switches. Now go back to where you started and get the jewels at the bottom. The lack of water will break the weak rocks. Now you can get the jewel at the top as the rocks can now be dropped without blocking the bottom up. Also get the jewels at the bottom center area.
Now hit the top depth switch on the right hand side. With the increased water, you can now get to the blue on switch. Go and press it. Now you can go back to the right and clear up the jewels, but remember you can't lower the water or you'll block the path. Use the blue air supply spaces to survive in the water.
Hard 16 - Switch and destroy
Using a rock below you, kill the monster that moves in the path to the side. You need it to blow the wall to get to 2 other monsters later. Now, the monster outside the wall area, guide this through the top arrow on the right hand side. A good way to do this is to take it all the way across to the wall, and then down level with the arrow. This means that you can now take another monster across this path, but move down some more so it can go through the second arrow, and then further down for the last. Now the 3 security doors are open, you can access the jewels and exit.
Hard 17 - Cave guardians
A very easy level thrown in to give you a little rest from the challenges. There's enough spare jewels so that you don't even need to let the monsters out.
Hard 18 - Monster path
Start by collecting a shield while avoiding the monsters. You can now use the shield to kill one. Use the other shields to take out the other monsters. With all the monsters there are 8 jewels spare, so try to avoid killing them up against the strong walls or when they're next to each other.
Hard 19 - Limited mine
Guide a flame monster through an arrow into the orange security mine. Now send the jewel monster through the arrow below that, so it will hit the mine and give 4 jewels. The remaining flame monster needs sending past the second arrow down into the mine.
With this done, you can now pass the bottom arrow and collect the ghost pill. Now work your way to the top through the weak walls. You will pass a wall with 2 keys and a ghost pill on the other side. Use the ghost pill to navigate back. You can get out from the bottom with the key, use the other key to get the jewels and then exit.
Hard 20 - Cave of madness
Blow a hole from the bottom left corner of your starting room. Now from the room to the left of that, plant a bomb on the left wall giving you access to the break jewel limits and the security switches (don't get the orb x 2 yet). Now go in the room below where you started to get your trail up to 10 jewels. You can now open the trail doors. Use this to go around and collect what you can get. You can use a bomb if your struggling to get the room full of orbs. Get to it from the room above. Once you reach the very bottom be careful getting the super jewels as you can't hold out long on the heater squares.
You should easily get enough jewels now and the orb x 2 can get you the orbs needed for the door to get to the exit.
Hard 21 - Blast challenge
This level isn't as hard as it looks. Start with getting the jewels in the room you start in being careful not to blow any up with the explosive rocks. Once you reach the top you can blow the mine by using the stack of rocks to the side of it, just let the top corner rock topple onto it. Once you have the 4 bombs, plant one of them where you collected the bottom one. Once through, you can let some of the rocks on the other side fall into the whirlpool so you can get to the bomb x 2.
In the room below with the mines, put a bomb in the bottom right corner to access 2 more rooms and once this is done, you can collect the stack of jewels and then blow through the nearby security walls with 2 bombs. You can now head to the top right area where the remaining jewels are, press the red on switch to activate the conveyor belt. Finally you need to kill one of the monsters to finish your jewel collection, just guide on of them into a mine. Your last 3 bombs should be plenty enough to open any of the 4 security door colours around the exit.
Hard 22 - Crumbling cliff
You need rocks from the rock generator but need to be very careful not to get too many. From where you start, move down 1 space and travel to the far right making a straight path under the generator. As you pass the generator and get a rock, push this left so its vertically between the exit and the set of silver jewels so that when you drop it to destroy the walls, you can get to these.
As you travel back right, the next rock that's dropped needs pushing to the far right side. Move the next rock so you can get to the red jewels. The next rock needs going next to the the rock at the far right. Use a final rock to access the orange jewels from their left. Once this is done, drop these rocks to destroy the walls. Be careful on the right side: collect the green jewels before dropping the second to most right rock.
Hard 23 - Overtunnel
Where the tunnel splits at the beginning you can do either side first, it doesn't matter.
Going right will lead to the top area. Firstly you need the silver key, create paths under the left and middle set of anvils to let the drop allowing you to get the key. Guide the monster into the orange mine that's in the middle of where its circling, or you can use the mine to the right of it. Now destroy the other 2 mines that aren't next to the exit by dropping a rock on them. Once you get the 2 bombs, use one to blow up the remaining mine. That's this area done
Going left from the beginning will take you to the bottom left area of the level. You need to get all but 2 rock through the inverter. One rock can't be taken there because of the whirlpool and the other because its up against a wall and can't be pushed.
Lastly you need to get to the right area of the level. To do this you need to get on top of the tunnel at the bottom center area. You can do this by using a bomb to blow some walls up and allowing you to step onto the tunnel from the side. When you get to the side, collect the remaining jewels being careful about the top few. You need to let the rocks crumble without setting any mines off, as you will probably end up triggering a C4.
Hard 24 - It's deep
Start by traveling down to the invincible. From here go left to get the far left bomb, activating a return point as you do. Plant this bomb at the nearby weak walls giving access to another bomb and some jewels. Now head to the bottom and pass the bottom center return point, and use the bomb to blow into the other walls for the bomb (don't plant the bomb where it will destroy the return point!). You'll probably lose the invincible and die at this point. The return point will save you. Now get the invincible from the opened up area. Go around the right edge to finish off your jewel collection. When end up at the last bomb collect it and blow the nearby wall up where it leads to the surface.
Once through, pass the return point and get the keys. You wont get to the surface now without dieing first, so when your invincible and oxygen run out, you will appear back at the return point you just touched where you can surface and finish.
Hard 25 - Journeys end
You firstly need to get one of the rocks away from the wall. Let the top one drop on top of the other and topple off. Now you can use this to drop it on the security mine. Don't deposit the jewels you got; you need them. Pass over the heater and orb, now drop the rock on the mine. Your trail will allow you to move down from the rock and back up again before it falls. Now use the ice to get to the top left area. Collect everything except the orb x 2. Guide the mouth monster to eat the orb x 2 then use your shield to kill the monster, where you can get 9 orb x 2's.
Go over the ice to get back, you need to go to the bottom through the arrow. Get the 6 bombs. You now use these to get the remaining jewels from inside the rocks. I suggest you plant the first bomb in the room you started in. Plant it at the wall so the 3 walls above the whirlpool will blow, causing some of the rocks to fall into the whirlpool. The last 5 bombs are enough to dig down through the rocks to get to the jewels you need.