Logic Masters Deutschland e.V.

Rules:

• Masyu: Draw a closed, non-branching, non-crossing loop along dotted gridlines. The loop must visit all given circles and follow these rules for movements:
  
  The loop must turn on black circles, and go straight through at least one vertex on both sides of the turn.
  
  The loop must go straight through white circles. It must also turn on at least one of the vertices it visits on either side of the white circle.
  
  Gray circles act as either a black or a white circle (the solver must deduce which).

• Star Battle: The Masyu loop divides the grid into regions. Place exactly one star into each row, column, and region, such that no two stars touch, not even diagonally.

Links:
Penpa+
SudokuPad