Computer and mobile games can be devided into three main categories: Strategic, reactive and braindead.
Success is based on planning your actions. Sometimes you have unlimited time to think, sometimes game goes on at some speed. In simple cases, the ultimate strategy is to gather and build everything (as fast as possible.) As simple as that is, it teaches planning ahead for children and older players.
If the basic concept of planning is clear, it’s time to move to more complex games that have plurar strategies but not one above all solution. For example Civilization series aims to that but there are plenty of others.
From educational point of view it would be best if the “right” solution would be different every time you play certain game, that leads to really think what is worth doing and what is not. If, anyway, the variations are only distractions like random disasters, that often results player just starting over.
Reactive games are somehow based on player’s quick reactions. Most first person games are like this. These are good for reaction time but too much playing can lead player being on the alert all the time even when not playing. Violence can be involved, too. Age rating system gives some clue, but is not equivalent to violence only. In UK, ratings are legally enforceable (12, 16 and 18 years.) In addition to that, it is always advisable for parent to stay in touch what game really contains and talk about it with their kids.
Last and very least, the brain dead. I’m referring to those games that require no strategy or right time movement what so ever. The simpliest for of this is when you tap mobile screen to get points. And that tapping goes on and on and on … It’s hard to belive how much time can be consumed to this kind of game. There is others, bit less obvious forms of the same idea (or lack of idea.)
If your kid plays brain dead games, it’s advisable to lead him/her to some other activities.
To sum up, nothing is good in too heavy dose, but strategic or reactive games in proper age and proper amount do more good than harm teaching to plan, solve problems, react and be part of a social group. For braind dead tapping games, there is no excuse.