I have an idea for the quests. Maybe you can put rewards up, and be able to choose which blocks you want to receive, or you just receive them randomly. Also, a market-like place where you can buy blocks for (if you add) xp that you earn from quests? I dunno. Just suggestions, although it would be great.
And tele porters. Get rare blocks (that you can buy) to form a teleporter to a different location. (ie. If you want to explore a different biome, you make a house and put a teleporter there. I hope there will be a compass to tell where you are. Or instead of buying blocks, use mana to teleport?
For weapons, maybe add like spears (to kill trolls like in the video) that you can throw and hit them with. Or instead use mana to transform them into a little creature.
If you add a market, maybe you could add spells for you to use your mana on, and upgrade how much mana you can have.
That took longer than I thought...