the menu screen came alive!

[catcatamelia]

ok so i was playing on my pc, i was afk on the menu screen because i was talking to friends and i don't exactly remember what it got triggered by but i clicked somewhere. i got distracted but then went to grab the mouse to play and the menu like turned into a playable space  i went exploring then i saw the wolf my first instinct was to run so i turned and ran onto a rock i thought maybe there's a easter egg in the house so i clicked on the door (surprisingly it was functional) but it led me to a black screen then i quit  i have a video but i only recorded part of it  

it was weird the player was standing on a rock looking exactly where the camera would look i was also having issues with opening steam in the background causing back screens

video

[catcatamelia]

other games have had issues on my computer (portal corrupt save, black screens on tld) but i have a realy good computer i realy don't think these have anything to do with this odd glitch though, im realy curious what caused this