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Level 243.4 is one of the four transitional hallway associate levels of Level 243. Looking at one wall, you can see Level 243 though you cannot get to it. Inside Level 243.4 there are multiple plants of different types, a circular table and four straw chairs, along with some hanged lights. The entire hue of the level is sepia-like, including yourself.
From here you can just turn around to re-enter Level 245 or you could continue going down to enter Level 244. Given you've entered the other three associate levels, then there will be an alternative door that brings you to Level 246.
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