Invernovasion is a project by The_SloVinator, started back in April of 2018 Its  aim was to make an atmospheric wad with environmental story-telling, as well as implement plot & maps that connect each other via exits/starts. It has custom stuff from names of the maps to graphics, like intermission background, to custom ending text & of course music and feels very 1994'ish in a positive way. The author recomennds to read the included text files so I suggest doing so as well :) Have fun with this interesting trip to the past.