I thought it might be a good idea to have a thread for this. Who doesn't have a smartphone or tablet or both these days and kills time playing games.

Here's some games that I have tried.

Pandemic
The only paid game app I have (price just went down, after I bought it, to €4.95 ). Probably the best cooperative board game on the market (since 2009) and a fantastic one-player game. You can vary characters (base game has 6), number of players (2-4) and difficulty level (4-6 Epidemic cards), for a fair amount of replayability. Buy the On the Brink expansion for 6 more characters, 5 players and additional event cards for more replayability.
Every turn you have to take crucial logistic decisions. There is no AI that can spoil game experience, you have to beat the cards. You don't have to worry about game state as in the RL game, the app does it all. Not a light game, but highly recommended.

This is a screenshot, where I pulled out a victory with 0 cards left in the deck and triple infected cities everywhere




Spades
A great card game, much better than hearts and almost as good as bridge, but not quite yet. The first I tried was Spades Free from AI Factory. Cool graphics, but the AI is abysmal, despite it peeking cards. The next one I tried is Spades by KARMAN games, The graphics are not as good, but the AI is MUCH MUCH better and in various games actually plays well. A little passive on the bidding and you will consistently beat him because he picks up too many bags. There are plenty more Spades games, but I never looked further. I never play online, just the single player game.

Farmassone
This is Carcassonne, for free. It has two meeples, tractors replace the Farmers and it has some different buildings and scoring, but it is basically the same thing. As a single player game, this sucks because the AI is more terrible than a drunken monkey placing tiles randomly. No challenge or tough games whatsoever. I haven't tried multiplayer. This app didn't stay for long.

Chess
I play Chess very few and haven't tried more than one app for playing strength. I don't need to, because I already lose to a bad AI like the one from AI Factory. The one app I kinda like is Chess Tactics, which provides you with 6 play problems every day (from really easy, to easy to moderately difficult).

I'm looking for more single player games, turn-based strategy if possible, that are worth playing and/or worth paying for. Absolute requirement is that AI is good.

San Juan qualifies -- a faithful adaptation of the card game.

Light go 13x

Minecraft PE

Wordbrain

Dominations

Clash of clans type but it has technologies you can research kind of like Sid Meiers Civilization Revolution, as well as choosing your starting Civilization (Japan, France, etc.. All with different perks). I enjoyed this as much if not more than COC

Edit: Missing a lot of the clan war stuff that COC has but just because it's still fairly new

Edit edit: when you attacks enemies your surviving troops actually survive. Makes it better for raid sessions

Niggle

Some might know it as Oh Hell; I've played it for years and years with friends.

Fabulous strategic trick-taking game; the only way you get points is by winning exactly as many tricks as you bid, no more or less, and the number of cards dealt varies with each round, so the relative hand strength constantly changes. There's deceptive depth and skill; I like it better than hearts, spades, or euchre.

Really, really great game to play at home with three to five players, but the app is a lot of fun as well.

Duet

Probably have heard of this one.

Arcade-ish style game, i guess? Good soundtrack.

Hard to describe well, but you control two balls that remain on the exact opposite ends of a circle, which you rotate as you dodge blocks falling from above.

Fairly challenging, and has speedrun modes as well.

I love this game! We call it Oh ****, and have heard it called "Screw your neighbor". When family friends have played it around kids, they refer to it as "How to best take advantage of your neighbor" lol

I would recommend the chess.com app. It also gives you 5 free tactics a day (adjusted for your strength) if thats what you're looking for. but you can also play people at any time. you don't need to worry about not being good enough because it'll adjust and give you a rating, so you'd only be playing against people who are similar strength. it also has tons of learning stuff, like instructional videos and lessons, if you were trying to improve. and it also has a computer you can play against which I'm sure can also be set to match your strength. so id recommend giving it a try if you're looking for the best chess app

We actually call it Bitches

Because we were playing one time and when my friend got screwed over she would call us all bitches

And the name stuck

Sword and Glory

Fun little dueling/sword-fighting game set in some middle/dark ages type medieval era. I was one of the top scores for glory or total glory at some stage I believe.

http://www.ifelsemedia.com/legend/

Website sucks, but you can find the links here. Game is free, you can spend money to buy in game currency, or use in game currency to buy the other type of in game currency at an (IMO EXTREMELY FAIR) rate.

Combat is fun, storylines are fun, would recommend.

Plague inc. is nice, you have to kill of the world with a dozen or something different plagues which all have their own difficulties in doing so. in general the dificulty goes up and you really have to strategise your way through, choose the right balance in alot of spots since we are not paying for **** our actions have to be quite precise.

from point of detection people start working on a cure, cutting of routes and quarantaining countries and people all with different levels of urgency.

and you can call the plague after yourself

Chalk me down as another who loved this as a kid. We knew it as 'silly whist'. I play it on the 'Contract Whist' app, the AI isn't perfect but it suffices for a quick game while commuting.

Silly Whist

you're so british

Try playing it as an adult

It's surprisingly complex

confirmed
oh yeah, it's still great

I tried this one, but when I had to tap randomly appearing bubbles on the screen to gain points, I uninstalled it.

I dont think those are random but its a while since ive played. i think those are points gained from the newly infected areas. if you see an infected vessel going to japan you can be sure some points will pop up there. I guess they couldve automatically put them with your total points but not to bad to get you a little involved in the process imo. its just a tap to get them anyway and time stops when you go in the menu

bump

Need some suggestions for offline games that are challenging, turn-based and either have a strong AI or independent of AI

Pandemic is getting old. I have no problems with paying for an app.

Star Realms has a good app and is a lot of fun imo. It's free and the AI is good.

Edit: I haven't played the boardgame version, but from what I know they're identical: https://boardgamegeek.com/boardgame/147020/star-realms

This was a really good recommendation. Star Realms is an excellent game.

If anyone knows the game, look what I managed to do:

• I have a 5-card deck that discards my opponent hand - a complete lock
• I have 310 authority, but that could have been any other amount
• The trade row is gone, I have scrapped the whole game.

I feel like a lot of classic games have been added to Android and iOS lately. I just bought Jaipur, Patchwork and Splendor for about $10 total. A year ago I'm pretty sure none of those were available, official releases of Race for the Galaxy and Castles of Mad King Ludwig are availble too. A great way to for a bit of newbie like myself to try out new games before potentially buying physical copies.

Initial review is that Jaipur, Pacthwok and Splendor are all great games, but Jaipur is particularly awesome for mobile devices. It also has an adventure mode that's actually worth playing.

Are these all games that you can play in single player mode vs a good AI?

galaxy trucker, excellent campaign, haven't tried the multiplayer

Antiyoy

free to play, turn based strategy with very basic rules

Yup.

Pretty sure the AI is solid, but I haven't played the games enough to really know what's good play.