This is my attempt to create a guide on how to beat The Witcher 2 on Insane difficulty. Accomplishing this will give you the Madman achievement. According to current Steam statistics, only 0.8% of players have achieved this (and 18.5% of players have beaten the game at all, in any difficulty).

I've seen several tips and tricks in various forums on how to go about achieving this goal. But after several attempts, once I've finally managed to reach this goal myself, I've decided to take the time and write down not only a few suggestions, but a more complete (and hopefully useful) detailed guide to this. So this is going to be a bit long. :-)

The guide below obviously contains spoilers for the entire game of The Witcher 2. I assume that anyone attempting to beat the game on Insane difficulty has already finished it at least once before. This also means that I won't give step-by-step instructions on where to find certain characters, how to solve riddles, or how to beat a boss like the Kayran - there are plenty of guides, walkthroughs and let's play videos for these (not to mention a lot of details on the wiki[witcher.gamepedia.com]). But I will give a few tips relevant for Insane difficulty for all parts of the game.

I highly recommend finishing the game once on Dark difficulty before attempting Insane. This really helped me out. Even though I've died many times while playing on Dark, by the end I've realized that it has trained me for Insane: Since on Dark difficulty you are so vulnerable to enemies you simply can’t afford to get hit, so the whole game you practice dodging, blocking and attacking from the flanks.

I've never before thought I’d try the game on Insane, but when I finished the game on Dark the fight with the dragon at the end was the easiest fight I had all game (and in the past, the dragon fight was so difficult for me, even on Normal difficulty). The fight was still a challenge, but I realized that if I can beat the dragon conclusively on Dark, then Insane should be within my reach.

And in the immortal words from another (much different) Guide: DON’T PANIC!

:-)

There are two main strategies for completing the game on Insane difficulty:

1. Take things slow and try to complete as many side quests as possible (except for the most dangerous ones). This allows you to level up more and buy better equipment, giving you a better chance at next battles.
   
2. Progress as fast as you can in the main storyline – skip all side quests. Your character will be a bit less prepared for future fights, but if you fail you’ll fail faster and can jump into the next attempt.

I've started with approach #1 above, but after dying twice I've decided it’s not worth it. Sure, following strategy #2 you’re more at risk, but the risk is there anyway. It’s very frustrating to spend so much time carefully advancing and building your character only to die 12 hours into the attempt from a simple mistake (or bad luck). While at the same time, these 12 hours could have been used for 2 or 3 separate attempts using the faster strategy #2.

To put this another way: while strategy #2 makes every encounter slightly more dangerous, it allows you to make multiple attempts for every single attempt at strategy #1, so for me #2 is the more efficient way to go.

So, the guiding philosophy is: If you have to fail, fail faster so you can try again faster. This does not mean you should be reckless. On the contrary, you need to be on your guard all the time, and at the first hint that a fight goes badly for you, immediately reload. But it does mean not to spend any time on anything but the main quests (with one exception – see below). As you get closer and closer to the end of the game, it makes more sense to spend a bit of time on upgrades, since you've already invested a lot to get to that point.

Try not to get too frustrated if (when) you die. Treat this all as a learning experience. Be prepared from the start to try this multiple times, learning from each one. When (if) you die, ask yourself: “What could I have done differently to reduce the risk?”, “Could I have paused that fight before dying and reloaded?”, “Why didn't I prepare for this fight with the right potions?”, etc.

One very important note before you begin playing on Insane: Several people have reported on the forums that if you play the tutorial at the beginning of the game and then beat the game on Insane the Madman achievement doesn't register (which is *very* unfortunate). If you're after the achievement, make sure to start a new game on Insane, but to skip the suggested tutorial.

• I’m focusing on the swordsmanship path as it works best for me.
  
• I’m taking Roche’s path, since I personally find it more comfortable and straightforward. Also, you get the David ability which helps against the dragon.
  
• Never pick a fight when you don’t have to.
  
• Try not to take any damage (lesson learned from playing on Dark mode). Invest a skill point into Feet Work as soon as the swordsmanship tree opens. Use Quen sign as much as possible, but don’t rely on it alone – learn to block incoming attacks on time. Focus on upgrades/potions/oils which increase damage rather than armor/vitality. Never allow yourself to get surrounded by enemies. Roll around and attack groups from the flanks.
  
• Try to never use your last Vigor point unless it’s an emergency – it causes you to do reduced damage.
  
• Use Swallow and Rook potions as much as possible (they’re fairly cheap to create, so why not get that advantage?). Grapeshot bombs work great, too.
  
• Get the following character abilities[witcher.gamepedia.com], since these are fast and safe to get: Pyromaniac and Sapper (you can get these two the first thing you do in the Prologue, before even meeting Foltest), Assassin, Experienced (start with the 5 training dummies in the Prologue; destroy the next 5 as the first thing you do when reaching Flotsam), Cover, Haggling.
  
• Don’t waste time hunting for resources, but collect anything you can in areas/rooms you enter anyway. Sell what you don’t need, especially weapons/armor/trophies which become obsolete to you. You’ll need the cash later. For the same reason, don’t buy anything you don’t really need until you get Haggling.
  
• Do the Mystic River[witcher.gamepedia.com] quest in Acts I and II, so you can craft the Vran Armor in Act III.
  
• Obviously, disable difficult QTEs from the options menu.

Since we’re not doing all side quests, we won’t get all the way to level 35. So we need to plan ahead which skills[witcher.gamepedia.com] are most important to keep Geralt alive.

Here's what I've used:

• Two points into Vigor Regeneration; One point into Parrying (with Quen on, you’ll almost never parry with full vigor in battle anyway); Two points into Fortitude (extra Vigor!); One point into Hardiness (or Dagger Throwing, if you like daggers. I’ve skipped this).

• At least one point into Feet Work (should be the first upgrade when the tree opens) and Position.
  
• One point into Riposte. This is very important – this ability sticks even when playing characters other than Geralt, such as in The Eternal Battle section in Act II, making some fights much simpler and safer. Use this enough and you’ll get the Parry ability.
  
• Two points into Violence; At least one point into Whirl; At least one point into Hardy.
  
• Two points into Precision; Two points into Invincible; Two into Combat Acumen; At least one into Whirlwind.

• Two points into Destructive Magic (extra Vigor!); at least one point into Enhanced Quen Sign; at least one point into Venting.
  
• If you feel you’re still short on Vigor, invest a point or two into Magical Vigor.

• If you use bombs a lot, invest a point or two into Alchemist (I didn’t feel the need).

The prologue is often considered one of the hardest parts of beating the game on Insane difficulty. It’s easy to die in the Prologue if you’re not careful, since your character is at his weakest, and you feel the urge to push forwards as fast as possible to the “actual” game. Consider this a training phase - teaching you to treat all challenges with the same respect. Don't take risks. Reload if things go poorly.

• Remember to start by getting the Pyromaniac and Sapper abilities, and destroy the 5 training dummies.
  
• Check around the ballista for the assassin's body to get the Assassin ability.
  
• Keep calm and take your time from fight to fight. Don’t take risks. Keep your distance and attack groups of enemies from the flanks. Remember that you can use the Swallow and Rook potions to give you an edge. Also remember that you have 5 Samum bombs, which can make the last couple of fights much easier (you’ll still have 5 bombs when starting Act I, so there’s no reason to save these).
  
• Convince Aryan La Valette to surrender, and later rescue him from the dungeon. Not only will you avoid a needless fight, but you’ll get the useful Strong Back ability.
  
• In the secret passage under the monastery (where you meet the first Drowner), there’s a destructible wall, behind which you’ll find a Temerian Sword (better than what you start with).

Act I is of medium length. Ignoring side quests, the only really dangerous challenges are the Kayran and Letho. Everything else is easy with some preparation.

• Remember to equip your Temerian Sword instead of your standard sword.
  
• In the beginning, stay under cover of Triss’s protective magic for the Cover ability.
  
• After stopping Dandellion’s and Zoltan’s hanging, go immediately to destroy 5 extra training dummies to get the Experienced ability.
  
• Craft a silver sword. Loot Einar Gausel’s house (directly across from the smith). You can find a better weapon, as well as Dwarven Enhancement (equivalent to Diamond Armor Reinforcement).

• Go to the inn to trigger the Kayran appearance, go and negotiate doubling the price (to get Haggling ability later), go talk with Cedric (buy from him the Grapeshot formula, and the Kayran trap diagram), go to the Kayran lair with Triss (the 5 Drowner pack is a good opportunity to use your Samum bombs). Remember to check the boat wreck and read the letters to start the Mystic River quest. Ensure that you complete this quest when you return to town - you need this for the Vran Armor in Act III.
  
• Wait until midnight, and go visit Loredo. Sneak into the backyard, and get the Kayran trap fragment and the Astrogarus’ Armor.
  
• After speaking with Loredo, leave the compound and meditate until morning. Go to the smith and craft the Kayran trap (not necessary, but I found it easier).
  
• Go to Silé and go after the Kayran (forget the Ostmurk). Before going down to its lair, drink a Swallow potion, enable Quen and save. Make sure you’ve leveled up (you should have 6 skill points at this point – you need the extra Vigor point and the Vigor regeneration).
  
• Pay attention to the Kayran’s tentacles and roll sideways when one moves to a position above you. Place the Kayran trap in the indicators and use Yrden for the rest. Remember to keep Quen up all the time. If you are hit, immediately reload. Do not take needless risks – when Quen is down the Kayran can kill you in one hit. If you pay attention and roll correctly you won’t be hit at all.

• Remember to loot the Kayran. Return to get your reward and follow Triss to the barge to question the elf. Tell Triss you’d love her company.
  
• Ignore Triss for a while, and go buy the needed ingredients to craft the Kayran Carapace Armor (now with Haggling, this is cheaper). You might need to visit a few merchants. In any case, visit also Sendler in Lobinden and get the diagram for Diamond Armor Reinforcement. Ask him to craft a few of those as well as the Kayran Carapace Armor. Equip it and apply 3 of the reinforcements you’ve just created. This is the best Armor you’ll get for a while.
  
• You’ll need to go back and forth from Flotsam to the Elven ruins / waterfall in this act. Since we’re skipping the Nekker and Endrega contracts, the forest remains dangerous, but there is one safe path: Go from Lobinden in the direction of the troll’s bridge (start in Lobinden’s watch tower and continue across the small stream). Slightly after passing the path on the left leading to the Kayran’s lair, there’s a small gap in the trees to your right. If you activate your medallion you’ll see a Circle of Power there. Cut through this opening and you’ll pass through a wide open area, next to the altar of Veyopatis and from there it’s a straight path to the waterfalls. You’ll encounter very few monsters along this way (if at all). Keep Quen on and roll all the way (you should have a talent point into Feet Work by this time, making this faster). No monster there will catch up with you and there won’t be enough to surround you.
  
• Go to the Elven ruins and Triss will appear there for the cutscene. In the Elven baths reject Triss to get the Resistance to Magic ability.

• Return to town and talk with Zoltan. He’ll escort you to the middle of the forest, and all the monsters are still there. Before exiting the town with him, drink Swallow and Rook, apply Insectoid Oil to your silver sword, activate the nearby Circle of Power and Quen up.You’ll meet plenty of Endregas outside (and the occasional Nekker). Keep rolling and attack from the flanks – don’t get surrounded and you’ll be fine.
  
• Fight the Arachas (Yrden is useful here – you can also roll around until the monster focuses on Zoltan, and then attack from behind).
  
• Be polite to Iorveth!! It's instant death if you're rude.
  
• Remain in the clearing for a while and collect the Sword of Kaer Morhen from the nearby skeleton. Then roll your way to the Elven ruins, drink Swallow and Rook, apply a whetstone to your steel sword and activate a nearby Circle of Power if possible. Then save and go up to meet Iorveth and Letho.
  
• Remember to keep focused. If the fight goes badly reload instead of taking chances. You can easily use Aard to keep him off balance and then do 2-3 strong attacks. Don’t try to hit too many times or he’ll block you and you’ll be vulnerable. Just hit him twice and roll back. If he uses Quen, roll around until it’s over and don’t get close.
  
• Remember to pick up your sword and his, as well as the Special Forces Sword outside among the bodies. Roll back to town to talk with Dandelion. Visit Silé’s room, and the brothel next door and roll to the waterfall to find Cedric.

• Roll back to town, talk with Roche and start the Death to the Traitor quest. Wait until midnight, sneak into Loredo’s compound from the back alley and sneak your way into the mansion. Sneak upstairs, kill Loredo and fight the guards down the stairs (bombs are very useful here).

Congratulations! You’re 33% of the way there!

Act II is longer, but most of it is not really risky. Skipping side quests, the only really dangerous part is The Eternal Battle.

• While escorting the party out of the wraith battle pay attention to Prince Stennis’s corpse at the foot of a large tree (right after the first group of wraiths attacks Dethmold). Loot from him his sword (it’s much better than what you have).
  
• Talk with the king and with Dethmold. Leave camp and talk with Zyvik. Go to Sabrina’s execution site, examine it and talk with the soldiers. Tell them to return on their own (thus avoiding a needless fight with Drowners). You can come back later to see their corpses.
  
• Back to camp; talk with Zyvik and the Relic Peddler in the canteen.

• To get the square coins, you can either save Odrin (completely safe but slow and annoying) or do the Butcher of Cidaris (one short and relatively safe fight).
  
• Talk with Dethmold and tell him about the traitors’ hideout before going to the brothel. Before entering the hideout, drink Swallow and Rook and activate Quen. Applying a whetstone can also help. When inside being attacked by Trout and his men, roll to the side door (where you’ll exit after the fight). There’s no “open” trigger, but click on the door anyway and Dethmold’s backup soldiers will enter to help you, making the fight trivial.
  
• Go to the path to the right of the camp (when facing it) save the soldiers from the Rotfiends and go see the visionary (the soldiers fighting the Rotfiends might only be there after you go back to see the corpses of the men you’ve left at the execution site). Pay the visionary (it’s faster), return to camp and talk with the Relic Peddler.

• Talk with Dethmold, get your reward and say you want to cross the mist. You’ll get Zireael's Armor – equip it and enhance it with 3 Diamond Armor Reinforcements.
  
• Cross the mist with Zoltan (you can use your medallion if you’re not sure about the right direction) and talk with the dwarves in Vergen. Leave town to go in through the tunnels – drink Cat, Swallow and Rook. When entering the tunnels, take the first left turn you have and take the door to your right in the middle of the tunnel after that. From there the path is straightforward if you check your map from time to time.
  
• Talk with Zoltan and Saskia and choose to return directly to the surface. Return to Vergen, and climb to the town’s back exit to the forest. Use Quen and just roll past all soldiers/monsters to the catacombs (they won’t catch up with you and won’t follow you into the crypt). Apply specter oil to your silver sword and fight the wraiths to the standard bearer ghost. Answer his questions correctly to avoid a needless fight, and take the standard and sword.
  
• Return to Vergen’s entrance (again, roll past all enemies with Quen on) and beat Skalen Burdon in dice poker for the spear’s head. Keep playing him and also win Princess Xenthia's Sword, which is the best sword you’ll have for now.
  (Actually, with Runes you can upgrade the Sword of the Dun Banner to be better, but the difference is small and I don't recommend spending actual money on runes for this, as you'll need the money later).

• Return through the fog to the camp; go to the Nilfgaardian camp; go see Dethmold and say it’s time to lift the curse. At the execution site, guide the king to draw the right shape on the ground. Drink the usual Swallow/Rook combo, and with Specter Oil on your silver sword trigger the fight and kill wraiths until the fight is done.
  
• Wait until midnight and go see the king. Fight off the two assassins – hit and run tactics, don’t take chances. Block & riposte is really useful if they get too close to you.
  
• Drink Gadwal potion and talk with Dethmold to trigger the vision.
  
• Run to the assassins’ hideout (you can roll past the harpies and bandits along the way). Be careful with the gargoyles and the one golem inside. Yrden is your friend – attack them from behind and stay back when they die so you don’t take explosion damage. Talk with Serrit and take the Negotiator (best silver sword for now).
  
• Return to camp, talk with Dethmold. You’re now ready for the only real challenge of Act II: The Eternal Battle.

• This is tough because you don’t have your normal witcher skills. Stay focused and reload the second you feel the fight isn’t going your way. Use block often and riposte when there’s an opening. You should have at least 4-5 Vigor points, as these carry over even when not playing Geralt. Be careful in the 2nd segment, running from cover to cover: If your timing is off, you’ll get killed immediately by the incoming arrows – you probably won’t have a chance to hit reload. When playing as Seltkirk, try not to get surrounded. After dispatching the first 4 enemies, you can lure the remaining four to come after you one at a time – just advance slowly until one of them moves towards you then pull back and fight just this one before advancing again.
  
• When fighting the Draug always have Quen up. Trap it with the Yrden and hit it from behind using strong attacks. This will not take long. If he calls for trebuchet fire, roll around and hope for good luck :-). If you get hit (Quen is down) I recommend to reload.

• After waking up, it’s your last chance to talk with the Mysterious Merchant (who is cheaper than the others). Buy Ysgith runes from him (I recommend you keep 5 with you for Act III).
  
• Run to the hut by the cliffs, and run back with Roche to camp. Kill all the soldiers and run with Roche through the gullies to Vergen. Don’t needlessly fight the trolls. Make sure to check the boat wreck to complete the Mystic River quest!
  
• Run through the tunnels in the same path you took before (using Swallow/Rook/Cat). In some cases, the monsters and mercenaries inside will be too busy fighting each other that you can actually roll past them and open the next door to proceed, thus avoiding a fight with them.
  
• When you make it to Vergen go directly after Silé. The single Golem shouldn’t be a problem (Yrden and attack from behind). When king Henselt and his soldiers come, you can stand just inside the door to the inner room so that they have to come at you one by one. Block & riposte makes the battle easier and faster.

We’re almost there! One more act to go!

This chapter is pretty straightforward. Ignoring side quests, there are only two challenges: Saving Triss/Anais and the dragon. I find rescuing Triss to be much easier than saving Anais. We'll also spend a bit of time on getting the best gear for these final fights that we can get with minimal risk.

• Run down the mountain path with Roche. When reaching the bottom, before going towards the guards, take the path to the right (but not into the cave). You’ll find two Arachas there, but it’s worth the delay and risk, as behind them you’ll find Deithwen – the best silver sword you’ll get (it’s almost the best you can find in the game anyway, and definitely the best against dragons). Enhance it with 3 Ysgith runes. Your silver sword is now ready!
  
• Run into town and get to the main square. Go with Roche and talk with Radovid. Go into the sewers and in their Northern part you’ll find the Armor of Ysgith and the diagram to craft the Vran Armor. Go to Bras of Ban Ard and craft the Vran Armor. Enhance it with 3 Diamond Armor Enhancements. Your armor is now ready!
  
• At this point you need a better steel sword. You can try going after the Caerme – it’s not too dangerous if you roll past the gargoyles, but this requires spending time in the previous acts to ensure you have the right ingredients. I recommend instead to sell everything you have and then buy the best sword you can from Bras of Ban Ard, such as the Short Elven Sihil. Enhance it with 2 Ysgith runes. Your steel sword is now ready!

• This is fairly straightforward. Just keep Quen up and use the regular potions, oils and tactics.
  
• Make sure Quen is on before starting this quest, and also before every new cutscene (you might get hit immediately after the cutscene!)
  
• Don’t get impatient just because the end is near. Stay focused and reload if you’re in trouble.

• With the Vran Armor you've already got a good protection from fire. I recommend as well as the usual Swallow/Rook mix to also drink Golden Oriole. Use a whetstone on you silver sword, Quen up, save and you’re ready!
  
• Run up the stairs, but wait for the dragon to finish breathing fire before progressing past the gap in the wall. If you've lost health during the climb up the stairs, reload.
  
• Try to get the dragon to breathe fire to one side of the room, then roll to the other side and attack it from that flank. Always pull back after 2 hits. Hit and run. Keep Quen on. With strong attacks it won’t take long to hit the dragon enough to trigger the next phase:
  
• On the roof just look out for the dragon’s attacks. Always roll back after hitting it. Always keep Quen up. Roll back or to the side if it attacks you. Ideally you won’t get hit once if you pay attention to its incoming attacks. Again, immediately reload if the fight goes poorly.

• Don’t fight Letho :-). It’s not a difficult fight at this point, but this is not the place to take even small risks.

Congratulations!!
And welcome to the club.

I hope people would find this guide useful.
Since this is my first time writing a guide/walkthrough to any game, comments are very welcome :-)