At first I thought it was just going to be a copy of the example game - but it turned around and was really pretty cool. I liked how tricky and unforgiving it was!
You grammar is not bad at all - and everything I saw was just minor typos.
One of the main things that could be improved upon is to pay close attention to your tense. Sometimes, you mix/switch between past and present. Like when you first examine your sheets, it says, “The sheet LOOKED dirty. I CAN’T believe…I GUESS they PROVIDE… All I WANT to do…” ‘Looked’ is past tense and the others are all present tense. So, I would change ‘looked’ to ‘looks’. Also, your option says, “Look at the sheets” - so I think it would be best to follow that with “The SHEETS LOOK dirty”. Basically just trying to keep everything consistent! I am noticing a few more little things as I read harder and harder into it. “I can’t believe EVERYONE would want to sleep”… should probably be “I can’t believe ANYONE would want to sleep…”. You should also try to not start a sentence with ‘but’. Either take it out so it reads, “I guess they provide some warmth”, or combine the two sentences into one like this: “I can’t believe anyone would want to sleep in these things, but I guess they do provide some warmth.”
Also in the mirror page - “You notice a small crack in the corner. Then a reflection catch you in the mirror from behind you?” should probably read more like, "You notice a small crack in the corner, but you catch a reflection of something behind you in the mirror.
I do not not have time to go through the whole game for you - and it might seem like I have made your grammar seem horrible — but TRUST ME - your grammar is very good. The things I have pointed out are very common even with native speakers!
You gave me some enjoyment with your game, so I figured I could give you some help with your grammar! Like I said before, I think the biggest thing you could really work on to REALLY perfect your grammar is to work on keeping your verb tenses consistent in your writing. I think this type of game should all be in present tense. I AWAKE with a headache. I KNOW something bad. As I slowly OPEN my eyes all I CAN see IS blackness. I RUB my eyes as I FOCUS.
Lastly, I noticed you also switch point-of-view (or perspective) which can be a bad thing. You start the story by using the word ‘I’ as if you are taking about yourself - but, then, you switch to using the word ‘you’ as if you are now narrating the story to the reader. Either way you choose, it should be the same. I feel like in this type of game, it is best to narrate to the reader. You awake with a bad headache. You know something bad happened to you last night. As you slowly open your eyes, all you can see is blackness. You rub your eyes as you focus. You think to yourself, “Where the hell am I - some kind of dark dungeon?” It is cold and damp. There are some dirty sheets on a bed, a mirror on the wall, and a door.
Hopefully that helps - and thanks again for sharing your game!