Card collecting games are often combined with other categories like RPG or Action. This makes them fun over longer time periods as you got much more to do than just collecting cards which would be a little boring.
If you like those type of game you should definitely try one of the games below. They can save your day if you got nothing else to do. As you have enough tasks to spend the rest of the day playing these games.
In Hearthstone you can play as all classes that you might remember from WoW or Warcraft 3. Each of these classes got their own special cards that can only be accessed by them. A lot of cards can still be accessed by every class to not make the game too hard.
Available game modes are offline campaign, PVP, or online tournament. Each if this modes got their own rewards but all of them are worth playing especially the single player campaign. Take care those fights might turn out to be very hard and unfair. You should only try these if you got some experience and already built a pretty strong deck.
Dragon Ball Z Dokkan Battle
I am already playing the game since it has been released and I did not stop playing it because of the updates and the big variety of characters you can collect. Events are also quite fun to play most of the times and best of all they always give you some cool loot that can only be obtained through the event for a certain time.
You might also like to check out: Dokkan Battle Hack tool
Pokemon Trading Card Game
The available game modes are offline fights against AI controlled opponents or multiplayer battles against other people. Multiplayer fights might be harder than playing against the computer but the rewards are also better so it is worth it. You should still make sure that you do not start to play against human players too early. Most of them are very experienced and already own a great team of Pokemon which was built for PVP.
Trading is also available even a market where you can sell your own and also buy purchase Pokemon of other trainers. To make some easy coins you can purchase cheap Pokemon there and sell them for more but analyse the price before investing into a Pokemon for this reason.