Wang Trains (Browser, 2014)
Don't, like, ask me to explain what Wang Trains is. It just is. It is this entity that exists. I love it.
I can explain how I found it, however. Cute Train developer Mark Wonnacott (Patreon link) CC'd my Twitter account (I have a Twitter! Did you know this? You should follow me) when someone he follows produced this not-game. That person is Alex Midgley. I have no idea who that is but LOOK LOOK AT THE TRAINS.
From what I can tell the game uses some sort of mathematical concept called Wang Tiles, which is hilarious and no one should change it. Now I Wikipedia'd it once and couldn't understand what the hell was going on, but I did fail Maths at A-level so it probably isn't my area anyway. What is my area is this: the game procedurally draws a series of train tracks, and then trains (represented by differently coloured rectangles) randomly spawn onto the tracks and roam them. The tracks don't connect for very long, so mostly the trains will go back and forth for a while and then disappear. But it's absolutely stunning.
Just, like, sit back and watch them for a while. Look at the madness of the web of tracks and gaze upon something mere mortals may never understand. It's a beautiful way to kill a few minutes.
"But where can I see this marvel?" I hear you cry. Why, click this link! Seriously though click the link. It'll be fun, I promise you.
(Thanks again Mark for the heads up and sorry Alex for taking so long to cover the game!)