After having played Amnesia, i looked for similar game and learnt that Frictional games had developed other games.
Then i went on gamersgate and took Penumbra Trilogy.
i liked Overture,enjoyed a bit less Plague, and i have difficulties to find interest for Requiem.
I wil try to finish Requiem, but i do not feel enthusiastic.
Overture was dark and gloomy, and really a good game.
Plague took place in a laboratory, that was less attractive.
And requiem looks like a portal game
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So i will give a 8/10 to Overture, a 7/10 to Plague, and 5/10 to Requiem(i know thats hard)