You asked what a Grenke is.
A Grenke is an animal which lives in Southern Germany and the Northern slopes of the Alps. It looks like a small deer, about half the size of a roe. Its front half is red-brown and its rear half brown-red. It eats insects and small animals - frogs, mice and the like - which it catches by baiting them with a lure hanging from its single horn. Despite this horn, it is not known to be related to the unicorn.
Like the Wolpertinger with which it shares a habitat, it is often claimed to be fictional. Unlike the Wolpertinger, but like actually fictional creatures like the Gryphon and the Elephant, it is sometimes used as a fairy chess piece. It moves like a Ferz, one step diagonally, but may capture two steps diagonally.
The first Grenke Tournament was actually a fairy chess tournament, in which all knights were replaced by Grenken (the proper plural, by the way). It was not a success, and subsequent Grenke Tournaments have been ordinary chess tournaments.
So now you know.
Grenke is the financial company which sponsors the tournament. But you knew that. What I want to know is: what's a Tata?