Over the past few days I've been trying out Stoneblock 2.

It's like skyblock, but you're surrounded by stone. It's a cool concept.

I also like that it's got quests to direct you through it (especially helpful for people who haven't played with mods for a while).

BUT...

it doesn't really work after you get past the very initial stuff. It stops being an interesting alternative, and just starts getting grindy and samey, with a lot of just.. waiting around.