A hell of a incredible couple of games that play with some interesting theories I've never heard of before, but needlessly, make a far more interesting interaction all together. These two games were out before the other Zero escape game that was released first on Steam.
Not only due to have multiple paths based on your choices and where you go, but due to the Morphagentic Field, it makes perfect story sense that you could view one timeline, pick up some information, then take with with you for consecutive timelines to unlock the true ending.
Both games have very interesting set ups and some very difficult puzzles, though not unfairly difficult. I recommend this to any fan of the escape room kind of game where you need to look around and attempt to find a way out of wherever you are trapped.