People with black screen aren't missing much.
You can move around. You get a slow attack (and I mean, so slow you can't avoid getting hit. It's basically like watching 2 extremely large, slow boxers brawl it out, only one of them gets stripped as soon as she's hit).
There's nowhere to go sleep and regain health. Once you die, it's game over and you start from scratch. You literally have zero chance of making it passed 3-4 battles without dying, simply due to not being able to regain health.
The monsters basically fuck you till you die.
This game wasn't completed. It was rushed, and abandoned. The dev probably got bored and/or lost inspiration or got frustrated or something, and just decided to slap a completed tag on it and move on.
This game is garbage. That's the first time I've ever said that about a game, too.