LogiCue

LogiCue turns the daily puzzle around. Instead of guessing a hidden answer from hints, you run experiments on a number machine. Each day it follows one secret rule: it might add something, shuffle your number's digits, or report a property of the number itself. The day's machine is numbered and dated, with a difficulty label, and is the same for every player.

You type any number from 0 to 999 and press Feed it, and the machine log records what came out. You have eight experiments, but you do not have to use them all: the fewer you need, the better your result. When you are ready you press I cracked it, and the machine gives you three numbers it has never shown you. Predict all three outputs correctly and you win the day; miss one and the machine wins.

There is no vocabulary or trivia involved, only observing, forming a guess and testing it, and a round takes a couple of minutes. It is free with no account, and your streak is kept in the browser. Linerko's menu switches the game between English, German, Spanish, French, Czech and Slovak; the numbers stay the same. It suits players of rule-guessing games and anyone who likes number patterns.

The machine draws its rule from a set of about thirty, such as doubling, reversing the digits, the digit sum, or sorting the digits from largest to smallest, so a rule you have cracked before can return a few weeks later with different test numbers.