Listed below are only the ones that I liked.
This list contains all manga, manhwa, manhua, and webtoons that are related to:
→Survival
→Deadly Games
→Horror/Thriller
→Psychological Aspects
For a related list, but mainly heavy drama and detective cases, see:
http://www.mangago.me/home/mangalist/427834/ 
Messages
Oh! It's in my want-to-read list that I completely forgot about. Will try it out then (๑•ㅂ•)و✧
Try Escape room https://www.mangago.zone/read-manga/escape_room/
Very underrated
I just finished it. Wow. Thanks for the recommendation! (๑•ㅂ•)و✧
Try Distant Sky, its dark, hardcore psychological and great story line + its colored.
Yeah distant sky is amazingＯ(≧▽≦)Ｏ
(〜￣△￣)〜