Every other week, Greyscale Gorilla challenges motion designers to create something cool for their animation portfolios (that isn't time consuming) and experiment with new techniques by producing a five-second animation around a theme. The most recent Five Second Projects' theme: old video games.

GSG asked its readers to "remember the good old days when Mario ruled the world and first person shooters weren't around." The site is accepting submissions until July 13th, but it already has almost 30 entries that you can now watch online.

Many of the videos are mashups of classic titles like Dave Frank's video above ("A Little Help From My Old Friend"), but there are also shorts filled with game glitches and reimagined mechanics. Since the clips are so short, I've embedded a bunch of my favorites below. The Rainbow Island one in particular is aces.

"Old Video Games" by Deborah Anderson:

"Jump Man vs. Jump Man TM" by William Mc'Bergen-O-Shay:

"Asteroids" by Joey Korenman:

"5sec |: ...of old games :O)" by Bubunya:

"Rainbow Islands" by Stephen E.:

"Hogan's Love" by Jason Schevchuk:

"Over9000!!!" by Mat Cinque: