One is Gwent, which is mostly competitive but with a fair ecosystem. You gain enough ressources to fastly build up a competitive deck. Since develepment will end this year you will have to learn the rules only once. you can spend money too, but you can't buy any competitive advantage with it, and players mostly do it for cosmetics.
There are single player games out there too which are sold separetely on gog.com Thronebreaker is the better one imho, while Rogue Mage tried to adapt the somewhat popular Rogue mechanics. And then there is the gwent minigame in Witcher 3 which started all this...
The other game is Skylords Reborn which is a free reimplementation of the 2006 game Battleforge. It's a Fantasy RTS with TCG mechanics. Since the developers don't have the copyright for the assets it's totally free, ressources are earned by playing, and after a while you will literally swim in BFPs. Playing is mostly PvE which can be done solo or Co-op. There is a PvP section too, but since it's player base is rahther small you may expect some waiting time for making.