"RaceSwap" is an awesome, yet confusing mod where all three factions of StarCraft II get retextured to look and act like a different faction.
Protoss units and buildings now look Terran, while Terran looks like Zerg and Zerg looks like Protoss. Even if you are familiar with the game, with blinking Marauders and flying Hatcheries, this will make everything chaotic as hell.
The mod, made by TheSkunk, is now playable with Custom Games (All you have to do is to create a custom game with mods and search for the "raceswap" mod. And maybe invite someone without telling them anything about it).
Here's a short clip (with a lot of puns) by JaKaTaktv showing the mod's features:
I love how they made custom descriptions for the new, mixed-up units:
Ultralisk changes into: Depressed Templar
Tired of hiding in the shadows, Dark Templar decided to de-cloak and show who they really are, in order to be excepted by all of their fellow Protoss. This strategy backfired, as it turns out there was another reason Dark Templar were always cloaked: They look ridiculous. After being laughed at and mocked by all other Protoss, Dark Templar developed an eating disorder and have grown to enormous sizes. Fulled by rage and shame, these massive Depressed Templar, while no longer cloaked, can deal devastating AOE damage.
High Templar > Really High Templar (Viper)
Description: Just to show off, High Templar fly higher off the ground now and have learned some new skills, like Psi Cloud (instead of damaging units, it blinds them) and Psionic Abduction. (Sick of being left behind by the speedier Protoss units, High Templars learned to pull units towards them)