To muck up your brain, try Gestalt OS, Alien Keymap, Game Inside a Game, Zebra, Cell Machine, or Out of Ctrl.
Or some simulators like Sandspiel, Evolution, Nicky Case's Emoji Simulator, Snowman Simulator, or the Neural Self-Regenerating Cellular Automata.
For a relaxing ride, try Line Rider or Fly Like a Bird 3. For a ride not so relaxing, there's always QWOP.
Language and spelling weirdness can be yours if you check out Last Word and Galactic Center for Etymological Research.
Cursors 2 is fun with a friend, and the ancient yet brilliant GooGrid is good with a gaggle of friends.
Make a game or story with Bitsy, the Flickgame Engine, or just pretend by using Hackertyper.
For unbelievable e-textile cleverness, check out KOBAKANT.
All kinds of nonstandard and gremlinoid computing can be found at esoteric.codes, Dynamicland, the Vintage Computer Festival Midwest, and The International Obfuscated C Code Contest.
Nicky Case on how turtle graphics work
Gaius Fortunatus's Roman marching pack
Alice Maz on Minecraft Economies
Bret Victor on Learnable Programming
Terri Windling's Folklore Blog
Body Ritual Among the Nacirema
Justus on Self-Watering Plant Pots
Hunter Irving on a Hypothetically Simplistic Android OS
Bernadette Banner Sewing Pockets
Primitive Technology: Tiled Roof Hut
Building a Cabin, Start to Finish
The Hyperbolic Geometry of DMT Experiences
Norse and Germanic Mythology ASMR
BBC's brilliant, amazing, incredible Living History series, in historically chronological order: Secrets of the Castle (13th century), Tales from the Green Valley (17th century), Victorian Farm and Victorian Pharmacy (19th century), Edwardian Farm (early 20th century), and Wartime Farm (middle 20th century).
Open Source Order of the Golden Dawn
School of Machines, Making & Make-Believe