It looks to me like an example of a modded minecraft playthrough, minus the weight gain and inflation elements, I’d guess the quests are around either gathering certain items, defeating certain enemies or uncovering certain possible structures or other points of interest. In games like Minecraft, Terraria and Starbound, completing the game main cycle is simple, but not for that reason people stop playing it. With the same idea of being able to build stuff and fight enemies, you could experiment with creating more structures or finding weirder or better ways to fight certain creatures. Since this is just an idea, there can’t actually be too much of a definition in terms of what I’ve already said, or for that matter the combat system. Also, as I’ve seen that already being possible with certain games such as Kobold Dungeon, Coinpurse Kobold and Growth RPG, the weight gain could be made infinite, so the gamepaly could be made, although repetitive, possibly infinite.