In real time, this playthrough takes 13 minutes, 17 seconds. Sped up in the .gif above, it's 2:06. It's the amazing solution to a version of Snake, a genre of casual game going back almost 40 years, so old its original form is all but lost to memory.
This .gif hit a Russian message board about three days ago and went viral thanks to Reddit and imgur yesterday. The snake consumes 100 pellets exactly, increasing its length to 801 blocks, which is one block more than the cage can hold. Thus, this is a game that ends with a kill screen.
Watching it play out, I thought someone had written a bot that either forced the game to put pellets in optimal locations, or predicted where they would pop up, or directed the snake on the longest route to it (to avoid running into its tail). Slowed down, though, it appears to be a solution executed by a human player.