Draw a single closed loop that travels horizontally and vertically through the centres of all white cells. The loop cannot touch or cross itself. A set of letters that can never be consecutive along the loop is given; the letters along the loop are never an anagram of the given word.
(Rules (modified) and example (word = "ABC") from WPC 2016 IB)
History of the puzzle
First appeared on WPC 2016/Round 11, an "innovative" round. The author of the puzzle was Matej Uher (Slovakia).
A similar puzzle with all cells being occupied with numbers and the word being "ABCD" can be seen on Naoki Inaba's (Japan) website under the name アンイーブン ("Uneven"). 
Appearances in the past WPCs
- WPC 2016/Round 11 by Matej Uher