Amnesia: The Dark Descent
This game is pretty successful in creating tension by means of the unknown. The game never explains what the shadow is and what are the organic tissue that spread over the level when you complete some objective. Many times I had a jump scare moment caused by myself when I opened a door, it slammed on my face and I thought that there was someone on the other side. I was carrying a box and accidentally knocked off a glass bottle, which shattered and the sound startled me. This game also succeeds in making the player curious to explore every corner and sometimes you are startled by nothing. Nothing is there or there is a trap and you lose some life. A well with no visible bottom is also good in creating tension by making the player hear some monster that you don't get to see.
This game is a call back to old point and click games, which is also one of its major flaws. You collect items with no preferred order and this makes you become lost. Some puzzles are creative and you have to look for clues in the notes. One example is the elevator and the clue "8 up and 8 down". However, most of the time you have objectives and the fact that areas are accessible out of order make you gather items without knowing what they do or how to use them. When you complete an objective there is a screen flash and a victory music, which is similar to what Metro 2033 does to indicate that you achieved something. The lack of a checklist makes it hard to track what you have already completed and what is still missing.
I got all the endings but I didn't understand the plot. I had to read it on a site. The severely limited budget of this game is clear when you notice that all environments are closed spaces, there is a lack of objects to populate the rooms, a lot of repetition, very few voice actors and even an invisible monster. At least the invisible monster creates a tension by never showing itself and you don't know what that thing is. The mechanic to hide from monsters is a nice concept. However, I passed through the monsters by means of trial and error. They show up and if you let them leave without seeing you they just vanish. Most of the time I died because they killed me and after two or three respawns they just disappeared. The game never explains the monster's origins.
This game could be called Alone in the Dark because it's literally being alone in the dark from start to finish.