The purpose of Art is to make us feel and live through someone else's eyes ; someone else's experience.

This immersion, this projection, is often more important than realism. Realism can be very interesting but has it's own limitations : when reality has become common, how do you trasmit the feeling of someone for whom it is not common ?

The answer is : creativity.
That is why Star Wars' AT-AT is probably a better way to make us feel like a soldier of WWI facing his very first tank than a tank in a frame would be. Because for us, tanks are common, but for him, back then, it was a steel and plate invincible monster.

How do you show to a wide audience what is a mental illness without asking them to drop mad or get bored ?

Hellblade: Senua's Sacrifice is the answer to this. Developping techniques that were unique when developped, being backed up by psychologists and groups of people with mental illnesses, with the talent of good creators and artists, this game is make is us feel and live the adventure that is in the mind of it's main character.

Plain and simple, with no detour, with no compromise, with no false promise.

Plain and simple, because everything is thrown at us and we start quickly to think like the main character.
With no detour, because there is a goal, a destination, and nothing else. You have a quest. You promised.
With no compromise, because it was not ment to be bankable, it was ment to feel authentic, if not real. It was ment to make us question our way of thinking and change a bit part of us.
No false promise, because the very first warning screen is telling you : this is about a character with mental illness. And you deduce quickly ; she will have to face her own demons.
You will have to face her own demons.
Your own demons.
Be prepared to help her, and doing so to learn a lot on the way so it can help you later.

Unique, risky and impressive, this game should be bought by anyone having it on his wishlist but hesitating.

You are giving your money to a small dev team who decided to produce itself and risk everything on a game talking about mental illness.

Not very bankable.

But it was way worth it.

On the bad side, I would say that it is not for the hack and slash fan, and it can be hard on you sometimes. The limited number of "lives" (as said by the game, but I never went to the end of the limit) makes it a problem : if you lose all your lives, you will have to restart everything. To be honest, would I have lost the game, I would have stopped there, even if I WANTED to see the end. I would not have had the courage to restart everything from the begining.
Some small emotional parts have small problems : the character is crying but has no tears, making it strange, for instance. It doesn't happens often.

You understood it already : I cannot say anything else but : buy this game if you feel you are ready for this. Don't let it drop in the shadow of your wishlist.

It is an experience that must be lived.

It is Art.