How about make a rule - he can play mine craft for 1 hour in the morning and one in the afternoon (or whatever you think appropriate). And the rest of the time he has to do something else - some of which must involve some reading, and some maths.
Mine had great fun working out ratios - for example how big would their model car be in real life, how big their toy tiger, how small would the car be if it was the same scale as the tiger etc. Involves fairly simple maths, and can use a lot of tables. Maths - also in cooking - if we double the recipe how much of x do we need. If we wanted to make it enough to feed 20 how much would we need ?
Sit and watch a documentary with him - stop and talk about bits as they come up.
Get a magazine like national geographic - just flick through and look at the pictures - talk about anything at all that is interesting - for whatever reason.
Look at your area on google maps , then look at somewhere else - mine had great fun with that - found an active volcano with a lava lake in the middle of the ocean.
Randomly pick something on here and follow wherever it takes you. He might find that chameleons are fascinating.
One of mine spends ages reading What Car each month - and then following up things from it online - has done wonders for his reading :)
Maybe get him to plan his ideal holiday - let him google places to go, things to see, how much it would cost to travel, where to stay, how much it would cost.
Get him to find somewhere locally to visit.
Just try and think out of the box - don't go for academic stuff at the moment - he will still learn