Minecraft has a very particular feel that any existing mods I've played pretty much throws out the window to get their particular gameplay mechanics across. To make an effective, enjoyable, and minimally intrusive Minecraft mod requires getting being careful where you split apart vanilla to insert your changes.

I would love more ores to discover, but I don't want the end result to be more useless tiers of weapons and tools. I would love more ways to furnish homes, but there's little point in making more utilities that serve no purpose but to add another step to existing workflows. I would love lamp-posts and roads, but these things can be imagineered up from existing blocks, so any new variations need to provide some fantastic amount of value in terms of being attractive to players.

The worst mods I can imagine are the ones that simply provide a way to do an already existing workflow in Minecraft, faster than you already can. This seems pointless to me. I think there's a huge amount of player reward by performing some of these tasks. Waiting for ore to turn into ingots, or the like, is a reward for some hard work the player did. For the player to spend an hour or two mining, just to come up and have some infusion furnace or whatever turn their shit into ingots instantly feels fake.

Similarly, I don't want to give the player more bullshit grinding to do. I just watched a set of players try to kill enough Endermen to get enough Ender Pearls to turn into Eyes of Ender to find a Stronghold to put them in the Ender Slots or whatever and that's just ridiculous. The player should enjoy what they're doing, and look forward to crafting items, instead of seeing them as part of some arduous workflow, especially since Minecraft provides so little in the way of decoration or personal touches for player houses. As an example, think of some of the initial vanilla recipes. All you need is wood to create planks, sticks, and five varieties of tools. It's only one more step to create chests, doors, and crafting tables. Wide and shallow is the name of the game for workflows in Minecraft, with each step of the way providing some result that can be usable in may ways.

I can't even begin to imagine the amount of work it would require to make combat not such a terrible fucking chore in this game.

• Existing mobs would need some kind of animation or indication when they're attacking, possibly with a lead-up animation so their attacks can be dodged or blocked. Right now there's no way to tell how in danger you are of being attacked.
• Skeletons would need to pull their fucking bows and arrows back, and not be such annoying fucking aimbots. They should have to lead the player, and fire when confident.
• I don't see why all skeletons need to be archers. Sword-wielding skeletons would be just fine with me.
• Attacking should feel satisfying, and hitting an enemy should feel satisfying. Think about how good it felt to get off a shot with the super shotgun in Doom 2. Now think about how fucking idiotic it was to fight a mudcrab as a level 1 character in Morrowind. Combat in Minecraft is in mudcrab territory, and it brings the whole game down.

We have meat, and bread, but food doesn't go bad, and food doesn't stack, and the amount of hunger reduced from food is sort of nonsensical. Reduce the amount of hunger provided by all kinds of cooked meat. Meat and bread have damage meters which describe their quality. The lower the quality of these foods, the less hunger they remove, and the more likely the chances they will be tainted. Provide a knife recipe. A loaf of bread and a knife is consumed in a recipe to make 8 slices of bread. Two slices of bread and a meat of some kind create a sandwich. Sandwiches go bad, as well. I'm sure a knife can be used for other purposes, especially as a nice intermediary weapon before swords, but combat is such shit anyway so I don't know why I'd want to contribute to another pain in the ass weapon.

Aluminum should be used to make refrigerators, which can store food in order to prevent it from going bad. I'm not particularly concerned about realism here, so maybe food that's gone bad can be put into a fridge to remove its tainted property.

We have coal, iron, gold, and diamond. Iron and diamond make equally effective offensive and defensive items, and gold is near useless for everything. Not all ore should be equally good for all things.

Off the top of my head I can think of tin, copper, silver, and bauxite (smelted to aluminum). As above, I don't want to just create more tiers for weapons or tools, but the introduction of new tools needs to be significant. I keep thinking of the SNES Harvest Moon, where your basic tools did one thing, and then upgrading them did that thing extraordinarily well and reduced a lot of pain for the player. A wooden hoe might irrigate one block, while a copper hoe might irrigate a three by three area around the player. I like the association of silver with alchemical/magical properties, including increased damaged against vampires, or, in the case of Minecraft, the undead.

Some new ores should be usable in a recipe to create a shield. Shields can be hung on walls as a decorative element, or they can be combined with swords, as below.

Swords and shields should be usable in a recipe to create a sword and shield, which can be used in combat, and which provides a random chance to block strikes. Depending on the kind of metal used to make the sword and shield, different combinations provide different features. For example, silver sword and silver shield should provide a bonus defending against undead. I would love if putting a sword and shield back in a crafting table could spit out the respective items, but I'm not sure that's possible.

Tin and copper should be able to be combined to make a brass ingot. No need for furnaces or alloy furnaces or whatever. A door recipe with a brass ingot in place of one of the center wooden planks should create a lockable door. Placing a lockable door immediately provides you a key which you can name. The only way to open or remove the door is to use the key on it. Same goes for the chest recipe.

Brass ingots and glass should be usable in a recipe to create a telescope. On top of allowing the player to zoom, it should indicate other players, mobs, and animals in some distinctive way.

Using a lava bucket in a furnace and providing iron ingots in the top slot should create steel ingots. Steel armor should be more effective against lesser ores, just as steel swords should be more effective against lesser armors, but steel swords on steel armor should cancel each other out to a degree.

Grass should be used in a recipe to make hay.

One should be able to combine brass ingots and wool in a recipe to create cowbells, which can prevent livestock from wandering. Cowbelled animals should require hay, to prevent death. Animals without cowbells cannot be milked, sheared, et cetera. This could become tedious, but I have a sense that players will take pride in maintaining farms of animals instead of just huge pits filled with basically wild animals that are constantly attempting to escape.

One should be able to combine wool and glass in different ways to provide colored/stained glass.

I like the idea of totem poles, since they make easily identifiable decorations, and their basic composition fits well for a block-based game. In this way, people could craft totem poles with different sections, and stack them in ways that represent them.

Glass and aluminum should be usable in a recipe that provides windows with Venetian blinds. When powered with redstone, the blinds are open. When closed, they act to mobs as any other opaque block would. Perhaps combine with different colored wool to provide decorative blinds.

None of this entails going into the Nether. I'm not particularly sure if any of it should. I can't particularly stand the Nether, and none of this is endgame-level stuff.

Refrigerators would need to, every tick, both check on the status of all food in them, and, if we're taking the route that they also repair tainted food, continually check on the repair levels of each food item in them.

All owned animals would need to execute some custom AI state during every tick, though I doubt their AI routines would be any more complicated than the existing ones for dogs and cats.

The idea that swords of different kinds of materials might have different affects against enemies steps on the toes of the enchanting system. However, no one enjoys getting a Bane of Arthropods sword randomly anyway, so we might as well separate the kinds of enchantments that are provided, and the kind of effects that different material-ed swords have. That way, if someone really wants a sword to fight against undead, they can make it manually, instead of having to try and get it by chance. In this way, the enchantments are inclusive effects – knockback, no matter what kind of enemy, et cetera – and the material effects are more exclusive – increased damage against undead, et cetera.

I'm not sure how multiple kinds of totems would be handled. I would hate to add two dozen new block IDs just for the sake of decoration.

I have no doubt that the existing third-party mod interfaces to Minecraft wouldn't allow me to fuck too much with the existing mob AI, appearance, and behavior while in combat. That would require digging into the obfuscated code, I imagine.

I would probably designate the entire mod as having absolutely no guarantee of compatibility with any other mod. If people complain, then fuck 'em.

I have no idea if I can toggle the opacity of a block the way I'd want to for Venetian blinds.

Adding new ores would mean fucking with world generation. Not impossible, but I doubt it would be fun.