What is striduel?

A daily logic-puzzle race with four puzzle types, all solved by deduction and never by guessing: Paritu, a 0-and-1 grid that follows the rules of Binairo; Minesweeper Deduction, where every mine can be reasoned out; Code Deduction, a colour code cracked from clues in the style of Mastermind; and Pipsum, a dice-pip number puzzle that follows the rules of Kakuro. Beyond the daily sprint: Ringbreak, a Norse board game against the computer or a friend; Reflix, a laser duel in which mirrors bend the beam around corners; and Puzzle Golf. All guides: how the puzzles work.