.... it is bloody brilliant, the inventory, skills and etc., even crafting seems great addition to your maps. The levels are hard but fun, the puzzles / parkour sections seem fun and fair in a way too. Not even mentioning the many easter eggs, which are quite brilliant too :P
Now onto the problems and there is 3 main ones that really ruin the game experience by a good bit:
1. No path in the "Outlander" chapter (5th one, I think). After you get your loot from the thief, I there pretty much no path that would lead you in the city. I spend 30 minutes searching for the way out until I somehow parkoured on some cliffs, that didn't even seem like the right way.

2. Money and shops. The town where you can actually buy stuff is in the last chapter and basically there's not much use to it, since the game is pretty much over. Like, why not add small shops with potions and stuff to certain chapters? That way money would have use during the whole gameplay and not at the very end.

3. Dark Invader's boss fight. He just runs around until either all of us die or until he dies / turns into a dragon lol. He could have some more abilities, that would keep everyone on your toes like blizzard tornadoes, ice spikes coming down from the ground or really anything that would make him more than just a NPC with lots of health. It might be that ctx ran out of map script size again and couldn't make a good boss fight, but I'm just saying that it's not exacly good... better than the last boss fight in Rage though.

I would be proud it if CTX read this, I always loved your maps and in general, you're one of the big reasons why I still play CS:GO from time to time.