If you want a feel good, addicting game, I suggest Counter Strike: Global Offensive. It has a high learning curve, but when you get down in dirty, it's good fun.
If shooters aren't all your thing, LoL is a good choice.
And if you want something little known, kinda grindy, creative, generally fun, try Space Engineers!
I'd liked to see what others come up with... and I hope I helped or gave you some ideas.