After weeks of struggling I finally finished Furi the other day. At times I grew a little frustrated with it and put it aside, but I'm glad that I always picked it up again and managed to see it through.

Furi is weird little genre-blending game, borrowing elements from many different games. The entire game is a series of boss fights: you are a neon ninja cyberpunk prisoner trying to escape back to your world and each boss is a successive jailor. "The jailor is the key: kill him and you will be free."
There are no upgrades or different weapons, armour or any RPG elements. You start the game with all your abilities and controls and as you progress through each increasingly-harder boss you become stronger, not by upgrading but by actually improving your skill, your control and understanding of the game mechanics. Your character has two weapons: a gun and a sword. The sword can do light/heavy attacks as well as parry and dodge (with i-frames). You can use your gun for ranged attacks with a twin-stick shooter control scheme. Progressing in the game is all about learning the patterns of each boss and finding ways to counter their movesets. The combat is extremely satisfying, on the level of Dark Souls and defeating a Furi boss delivers that same satisfaction.
Each boss is entirely different and will use unique and often surprising attacks and their environment to try to kill you. But the intense boss encounters are broken up by these peaceful exploration sections where the narrative is developed. Each boss inhabits an entirely different realm and as you approach the next boss, you can explore his/her world as you begin to slowly reveal the story (of the game-world and each boss) and the mysterious past of the protagonist. These "walking" sections offer a calm, quiet rest between fights, a nice way to break up the intensity. The overall appearance of the game is bold: lots of neon, crazy 70's hair, strange architecture, and carefully-chosen colours. Combined with the entrancing beat of the electronic soundtrack (reminiscent of Daft Punk), this game-world is positively oozing with style and flavour.
Originally I wasn't going to play Furi because I'm not a big fan of bullet hell games, and the art style didn't appeal to me. But I'm glad I decided to give it a go because I eventually got into it and really enjoyed it (and the bullet hell sections are minimal).
In terms of challenge, this game is tough as nails. Even the "tutorial" boss gave me a lot of trouble to begin with and I definitely struggled through other parts of the game. But the controls are tight, the fights are fair and no death ever felt cheap.
Now for a few small complaints. Firstly, the game has four alternate endings, one of which happens half-way through the game (if you make the wrong decision). This happened to me and it wiped my save file, so I had to start the game over from the beginning, which was extremely frustrating. For anyone playing this, I suggest backing up your save file into a folder after you beat each boss... the game should really have the option to save manually. My other complaint is the final boss: I expected the fight to test all of the skills I had developed up to that point. Instead, the last fight is a big gimmick that puts you in a little "mini-game" uninteresting, frustrating and unrelated to the previous fights, and gives you unfamiliar skills, weapons and camera. Personally I thought this was a big blunder in terms of game design, and it felt completely out of place compared to the rest of the game which I enjoyed so much! Still though, it was tough and it felt great to finally beat the game, the final boss, and to unlock hard mode!
For anyone who likes a challenge, I would highly recommend Furi. It has a really unique vision, atmosphere and art style.. refined, addictive and satisfying gameplay, a wonderful thumping soundtrack, a formidable challenge and a brilliantly-executed narrative.