Edit (path-to-game)\DATA\ENGINE_SETTINGS.XML. Search for resolutionX & copy the whole line. Paste above it, changing for your resolution (4 nums, , no border *) & incriment precedence #. In-game, select windowed & your PLP resolution. ShiftWindow (+ border = borderless).

(PLP screenshot with bezel effect)
NOTE * Deprecated: tester used "resolution+border" values in XML, which is not strictly proper.
View guide for general help with the instructions.
File Attachments:Alien Isolation 2014.jpg