Here are my two cents:
I've now invested over 6 hours into this game and I really enjoy the gameplay. The problem is that I wasn't yet able to proceed past the first boss. I was able to reach him a few dozen times and managed to hit him twice or thrice, but that's it. And after playing through the second half of world 1 again and again, I eventually get so frustrated, bored and careless that I have to stop playing, because it brings me nowhere. And when I start the game again on another day, I'm back at the beginning of the game instead of the crystal that I have already reached.
So I'm now at a point where I feel cheaply cheated out of seeing and enjoying the rest of the game for which I payed. I've seen youtube videos of people defeating the first boss, but they didn't help me. There seem to be no cheats to access the next world. The save file is hidden in some obscure place, so I cannot just use someone else's save, where the other levels have been unlocked. I'm aware that there exist trainers for Volgarr, but I don't know if they work for the gog version and I'm not the type of person that is willing to mess with the game files in such a way.
So I am frustrated and disappointed with Volgarr right now, and I think I have every right to be, because I feel I have invested enough time, energy, and money into this otherwise great and fun game that I should be allowed to at least see world 2 now.
After playing some more hours after my previous comment I´ve earned ending "C", and I seriously think the first two worlds (specially the second) are a lot longer and harder than most of the later ones. Yeah, I know, supposedly later worlds have more complex enemy, hazards, etc, but generally they are shorter and even some of them have some easier alternate paths (like 3-1). They are a lot less boring too.
For me 1-2 and 2-2 were really annoying and the levels I´ve spent more time in the game. Maybe more in 2-2 than in all the later levels together, and I´m not kidding. The only reason I´ve managed to beat 2-2 is because I´ve ended searching how the hell the boss moves on Youtube. I spent like 5-6 hours easily only to reach the boss for the first time, and it killed me like 10+ times easy without even learning its movements. Later bosses are a lot easier to memorize IMO, specially as they are slower.
The worst was reaching the World 6, only to see that it features constant checkpoints (to the point you barely memorize in some rooms), even one previous to the boss. Why is this world different? Just because it features the cheapest enemy layouts? Why not extend this to the other worlds? What makes it so different?
For those having trouble beating the first two worlds, I would personally advice:
1-2: Learn how to pick all chests. All of them are easy and can be earned safely, even the more hidden ones can be picked with nearly 0 risk. If you manage to get to the boss with the flame sword, just jump the first attack over while throwing a spear to his shield. Double jump on the spear while using a second one. Jump on the second one and if you landed it high enough, you can just smash the attack button until the boss is dead. He won´t attack a second time. A lot easier than taking it slowly, as minions spawn at a different time frame that his attacks, and that´s what made the fight harder for me.
2-2: Again, try to learn how the get all chests. One or two of them might be trickier and can be left alone if you already have the flame sword, but they can be earned with little effort too. I highly suggest to learn to jump away from ropes, use a spear and double jump again to the rope, as it really makes some parts easier. If you have trouble beating the boss, watch a video of it, as this level is loooooong. Once you know the pattern it isn´t hard at all. BTW: I hate slimes (and generally all infinite spawning enemies, but these are the most annoying for me).
A great tip too is that whenever you find a buried sword, there´s a hidden hammer close, which can really help if you can´t figure out a part of a level or make a mistake.
I would suggest people to try some more. Later worlds were less painful. Anyway, I keep thinking this game would be really better with some more checkpoints. At least on bosses.