Most games on this site can be played by a child. Rather fewer are built for one, and the difference is visible in three specific places.
Is there a failure state? This matters more than difficulty. A game a child loses at is not a problem; a game that sends them back to the beginning is. The care sets and the colouring books have no failure state at all — a wrong tap costs nothing and nothing is ever lost. The arcade games and the timed puzzles do, and while a six-year-old can enjoy them, they will need somebody nearby when a run ends badly.
How many actions does the control need? Single-action games — tap a card, fill a region, drag one thing onto another — are workable alone. Games that combine movement with timing are not, at least not without practice. The memory sets, matching games and colouring books all fall in the first group.
Is the session length reasonable? A game designed around a short attention span ends before the child does. The jigsaws at their lowest piece counts, the shape-matching sets and the simpler care games all finish inside ten minutes, which is the right shape for this age.
One caution worth naming: some sets described as being for children have a harder variant hidden in them. The memory game where every card must match the first one you opened is a genuinely difficult exercise, not an easy one, and it is worth knowing that before handing over a tablet.
The children’s section of the site collects the games that meet all three tests. Everything in it can be played alone by a small child without anyone having to explain what went wrong.