I have a tendency to leave programs running overnight, resulting in 1298.8 hours for the Portal 2 mapping tools, and 861 hours for Portal 2.
...When every time you play any game you start thinking about how you could make it work with the source engine. To the point where you cant even play minesweeper without doing so.
Source would be terrible for most games. Which is probably why most games don't use it. When the only tool you have is a hammer, etc. etc. however that saying goes.
...when you realise that you have a 9.8MB, 1,254,358 word, 5,474 page log file for one of your maps. O_o
...when playing other peoples maps, (Cs:source, HL2, etc..) you spend your most time of looking for details and mechanics in level, not gameplay.
when you try to shoot a portal next to your bed to get up, and then you think that you forgot to add in the entity. (true story! the light in the bathroom parallel to my room is orange.)
You know you've been designing levels for too long when you walk around the corner of a hallway and think about how crappy the angles are entering that room and how it's too strong of a camping spot, and then turn around to look at the hallway to see if there's a better angle to build the choke-point, until you realise that you're standing in the corner of a hallway in real life and other people are walking by looking at you weird -_-
"Who has shifted time by 5 hours!?"