There's the odd pirate reference here and there in Valve's DOTA 2, but that wasn't enough for this mod. No, the creators of the STS Pirate Language Pack wanted to essentially relocalise the game, so it could be understood by toothless nautical bandits of the 17th century.
Serving as a "complete rewrite of the entire language in Dota 2", the pack has, after two years of development, been released to the public. Why two years? Because it's a Steam-wide project for the services baked-in localisation, meaning that while a DOTA 2 patch is the first to hit the internet, there are more planned, with Team Fortress 2 next.
If you're in the DOTA 2 beta, you can try it out below.
STS Pirate Language Pack [Steam Workshop]