Vertical Drop Heroes HD

This is the hardest achievement in the game. You need to play from Level 1 and complete the game, avoiding the use of the Teleportation Shrines that show up in levels, and never using the one at the temple you're in between runs. This will be virtually impossible without a few things.

First and most important is the Dwarf Turret ability. The final boss of the game is so unbelievably unfair that I can't see how it's possible to beat him without the Dwarf Turret. I got to him three times without the Dwarf Turret, and I don't think I even landed a hit or two on him before dying. You need to beat him six times in a row to beat the game. That's how ridiculous the final fight is. The Dwarf Turret makes the final fight a cake walk. Unfortunately, you're entirely reliant on RNG to unlock the Dwarf Turret in the first place. The red haired Merchant that shows up randomly in levels will be selling a single skill or ability. You just have to cross your fingers and hope it's the Dwarf Turret. Always carry a few hundred coins on you just in case you find it, to be sure you can afford it. You may get lucky and find the Dwarf Turret early for purchase. I didn't find it until a solid 8 hours into the game. Once you unlock it, DO NOT buy any other abilities from the Merchant. Doing so will only make it harder to roll a character with the Dwarf Turret ability. Once you have the ability, it should go without saying, but reroll your characters at the start of each run until you get one with the Dwarf Turret ability. 

The second thing you'll need to do is level up the Blacksmith and Apothecary quite a bit, just so you have a chance of surviving all ten levels to get to the final fight. Blacksmith upgrades are obvious why they're important, but don't overlook the Apothecary. Enemies and especially environmental hazards do huge damage in later levels, so if you don't have your health upgraded, it's really easy to Die in only a couple hits. The more your health is upgraded, the more mistakes you can make and the more crappy RNG you can get through. The amount of upgrades that'll make the game easy enough to beat will vary based on personal skill. I would say there's virtually no way you're going to succeed with each under level 15. I was level 25-30 on both when I succeeded in unlocking this achievement, but most of that time was spent trying to find the Dwarf Turret (and sometimes getting to the final fight but failing miserably, as noted above). Getting each to level 20 is a solid goal to aim for. 

With those two necessities done, there are a few other things you can try for to make this easier:
 

• Getting the Lightning ability from the Merchant is great. It's extremely powerful, and can make many crappy RNG parts of levels much easier to get through. Unfortunately, you're once again at the mercy of RNG to get it. I personally spent over 10 hours getting the completion in this game and still never got Lightning from a Merchant. 
• The Lockpicks ability is great to have. Not only does it allow you to open all chests you find, without needing to use keys, which is great for getting coins so you can use shrines, but also because there's almost always a health potion inside chests too, and these heal you significantly. The other good thing about this skill is that it means that all the keys you do pick up can be used to unlock cages, freeing allies to help you in each level. 
• Other helpful skills are Slayer (50% more damage to big enemies and bosses) and Gifted (double the abilities), but neither is really necessary, so don't fret over them. I got Gifted right away, but never found Slayer in my time with this game. 

As for the actual strategy, I have outlined the basic gameplay strategy in the roadmap, and by now you likely know what you're doing, but here is some more advice for attempting this achievement. 
 

• Level up as much as possible in the early levels, where the risk is low of dying. Enemies and traps don't do much damage, so focus on getting Pacifist Orbs and then killing everything, activating all alarms and all shrines to spawn more enemies. 
• In the last few levels, especially the last two, focus only on getting to the bottom. Don't go out of your way for anything, especially Pacifist Orbs and enemies. Take the safest route downward and take zero risks. It's not worth losing a run at this point. 
• If you've built up keys, either because you have Lockpicks or just generally amassed them, skip the boss of level 10 for sure, and consider skipping the bosses of levels 8 and 9 too. It's not worth risking dying. 
• In the later levels, descend very slowly and pay extremely close attention to what is visible as you descend. In particular, watch out for fire traps that count down and explode. These destroy the ground, and if you aren't paying attention they can drop you down and completely ruin your run. 
• The other extremely important thing to look out for is the white electricity node enemies that can spawn. I've only seen these in the later levels, but they aren't relegated to a specific level, unfortunately. These enemies are stationary and shoot a bolt of electricity at you. It does absolutely massive damage and goes through everything on screen to hit you. There is absolutely no way to avoid it. Literally all you can do is, if you see one become visible as you descend, make a beeline right for it to destroy it, or go down even farther to push it off the top of the screen. Unfortunately, if you see one, it means you're going to encounter a bunch throughout the level. I've literally never survived a level with these extremely OP and unfair enemies, so good luck if you encounter them. 
• If you're flush on keys and plan to unlock cages to free allies to help you, be extremely careful with the winged shield ally. This guy shoots straight down and destroys the ground. Like with the fire traps, this can catch you off guard and completely ruin a run if you get dropped into a really bad situation. If you do free him, stay away from him. 

Even with the Dwarf Turret, very upgraded Blacksmith and Apothecary, and all the advice above, you still have to hope for good RNG in the later levels. Sometimes the levels put you in barely winnable situations, whether it's lava, spikes, or sheer enemy density. It's so easy to make one mistake and die in seconds, losing your entire run. That's why you need to make the most of the earlier levels, and treat the later levels with extreme care, avoiding as much as you can. 

Once you finally reach the final fight with the Dwarf Turret, it should be clean sailing from there. Place your two turrets, hide, let them do their thing, and after each wave, place another two turrets. The first wave will be the tightest since you'll only have two turrets, but as you keep amassing turrets after each wave, they'll get easier and faster. Don't attempt to fight any enemies yourself. Stay hidden and let your turrets do all the work. The following video shows a playthrough as well as the final fight. Full credit to the creator of the video.