The '80s called: Usborne Puzzle Adventures
I've recently been thoroughly enjoying redoing the Usborne Puzzle Adventure series with my son (just turned 6). He's at the age where he can do some of the puzzles by himself and most of the others with a little help, which make them a great joint activity. A child a little older could do them independently.
For those unfamiliar with them, they are stories where on most pages you have to solve a puzzle to proceed, the puzzles typically comprising a mix of observation, mazes, simple codes, map puzzles and logic puzzles. There are pictures on each page and these are often integral to the solution - and sometimes you're required to go back and notice or remember something from a previous page. There's also a clue for each page in case a prompt is needed as well as answers.
The stories themselves are exciting and adventurous, with titles such as The Incredible Dinosaur Expedition, Time Train to Ancient Rome and The Intergalactic Bus Trip, and typically follow a small group of children (different in each case - with the except of the Agent Arthur subseries) who have to solve the mystery, investigate mysterious happenings or foil the baddies.
An added charm is that they have a wonderfully '80s/'90s approach to quality control, particularly in terms of puzzle difficulty. Although certain types of puzzles do come up regularly, occasionally an incredibly hard one appears, that clearly the setter didn't realise how out of whack it was with the rest and, notably, neither did anyone else before it was published. The most egregious example of this is in the Incredible Dinosaur Expedition where, after a series of puzzles aimed at 7-9 year olds suddenly, on the antepenultimate page, Bam! A question that wouldn't be out of place in a GCSE physics paper.
"The lava is heading for that ledge. Freddie has to run eight metres to pass under its midpoint and he does 100 metres in 25 second. The lava flows two metres in a second. It's six metres above the ledge which is 17 metres from the ground. The Monstermagus is 16 metres behind Freddie, runs six metres a second and we already know how tall it is. Can you work out what happens?"
The Vanishing Village is also noticeably harder than all the others for no apparent reason, to the extent that most of the puzzles take me - a reasonably intelligent adult who likes puzzles - several minutes and pencil and paper to solve.
Overall though, despite (or even because) they are fantastic and my son has been gripped, so would heartily recommend. If you don't have a dozen kept from childhood as I do, they are readily available from Amazon Used and New.
Disclaimer: Posts about things I personally enjoy doing, in my spare time, with my children, should be considered entirely as personal opinion with no bearing upon my thoughts on education policy!