As soon as I saw this jam, the very first thing that came to my mind was Tux Paint, a Paint-like program I fondly remember from the primary school computer room. Though I feel it's ~aesthetic~ is a perfect fit for this jam's theming (see what I have so far of MINDSALAD below for examples), I'm not too confident it technically qualifies. I have two main inquiries:

1: Is the use of any "non-serious" art software valid for this jam?
2: If #1 is true, do Tux Paint's stamps in particular violate the no outside media rule? They are part of the program, but do feel like outside media, and are provided as a separate download.

I think that looks incredible, but I'm leaning towards saying that the photo-stamps are a little outside the scope of this jam. I certainly wouldn't outright disallow that software, however.

I feel torn because as you say, this definitely fits the aesthetic of the jam -- but waiving that rule means opening a floodgate of potential design complexity. I'd rather folks stick fairly strictly to the listed rules, so the barrier to entry remains extremely low.