randoma11y - Generates two colour palletes that have good contrast, just like some parts of this site. :eyes:
Hemingway Editor - A bunch of useful tools for writing, including showing what sentences are hard to read, the readability of your text and even how long it takes to read it.
Cognitive Biases - A cool list of biases people can have.
Polyforms - You know those shapes in Tetris? There's a whole bunch of those, called polyforms.
Tic Tac Toe variants - Alternative versions of the classic game Tic Tac Toe.
Cellular automaton - Giving rule sets to cells/pixels to create mass life, really cool. Conways Game of Life is one of these.
Paper and pencils games - List of games you can play just using a paper and pencil. Most of these are 2+ players though.
Mariko Aoki phenomenon - A japanese phenomenon, about having to go number 2 when you enter a bookstore. There's even conspiracy theories about this. Weird stuff man.