Jeppe Norsker's OTLO Stones is an abstract pattern building puzzle game that you can play solitaire or as a competitive 2-4 player game where players are racing to win challenge cards by being the first to complete them.
Each player has six double-sided tiles. On each side, tiles show various combinations of either two or three shiny red, blue and yellow gemstones plus either one or two holes where a gemstone would otherwise be depicted. The 60 challenge cards are divided into three levels of difficulty, with the easiest (Level 1) requiring only a 2 x 4 grid of gems to match the pattern. You can overlay tiles to make the requisite patterns; so, for example, you can fulfil a requirement for a blue gem in a particular position even if the gem is covered provided it's covered by a hole through which you can see the gem.
Some of the Level 3 challenge cards may leave you stumped but you can be assured that there is always a solution, and Norsker Games include in the box a cheat sheet that proves it. We've especially enjoyed playing OTLO Stones as a 10-15 minute solitaire challenge. If you find the competitive game is skewed by one player being much faster than others, the rules suggest a handicapping system by way of a catch-up mechanic. It's an option you might consider when an adult is playing against a child - tho' it may well be that it's the adult who may be most in need of the catch-up mechanic :-)