anyone of you here can recommend any such games that you have been playing for at least 3 months and still playing.
Gumballs and Dungeons. It is like Dungelot : shattered lands but utterly massive. I have played for nearly a year and only scratched the surface. You categorically do not need to pay a penny, it’s just slower progress.
I've been playing Final Fantasy Brave Exvius for... I don't even know how long at this point, definitely longer than a year.
The only f2p game I'm currently actively still playing at the moment is Marvel Puzzle Quest. A bit on the fence if I should recommend it, it's a match-3 game with a fun core gameplay, but it takes some time to get anywhere and for a long while you'll constantly be fighting the scarcity of premium currency (that is used to make space to recruit characters), trying to push you to purchasing. There's also a lot of RNG involved in recruiting characters (currently 150-ish I estimate).
Marvel Future Fight still holds my attention. Over 150 characters to the game and enough things to do to keep one busy for hours on end daily. Plenty of paywall around but still a decent enough balance of f2p to genuine free to keep things from feeling too offensive. Especially for new players with the highly generous tutorial system and etc.