I have been playing Minecraft with mods off and on for a few years now. Instead of installing huge mod packs, I generally prefer to play only a few at a time, and I typically play just one major mod with a handful of support mods. When I play with multiple major mods, I generally find myself focusing on only one of them but rarely more. I recently analyzed this behavior, and I found that the reason is economics.
Vanilla Minecraft has a pretty good economic balance. I have a few complaints, but they are mostly the consequences of my play style, not any clear flaw in the game. I generally prefer to focus on exploring, gathering, and building. I don't spend a lot of time on combat, and I never go out of my way to find and fight bosses. I prefer to make mob farms to get drops rather than fight them on even footing. This means I don't get a lot of Ender pearls, I have never obtained a Nether Star, and I have not even gone to the End, let alone defeated the dragon. This works well though, because Ender pearls are mostly used for finding the End, which I have little desire to do, Nether Stars are good for building beacons, which mostly boost combat stats which I don't care about, and all the Ender Dragon provides is a trophy and experience (which can be obtained from a good mob farm). In short, the economics of vanilla Minecraft work fairly well, even for different play styles. Perhaps the only real complaint I have had is that rails cost a lot of iron and gold for any significant distance, and getting the materials is incredibly time consuming. As a result, I don't use rails much anymore, which is a shame, but the game is still fun even without them. For the most part though, the economy of the game is well balanced, allowing resources to be obtained as they become needed without costing more time than they are worth.
Mods, on the other hand, often fail at economic balance. The least susceptible mods to poor economics is mods that add their own resources to the game and use built-in resources minimally. They are successful, because it is easy to balance your mod with new resources that are not used for anything outside of your mod. Most mods don't do this though, and even many very popular mods fail in economics. Recently, I have played using BuildCraft, MystCraft, Immersive Engineering, Thaumcraft, Twilight Forest, and Botania. These are all fairly popular mods. They are all very well made. But most of them have at least a few economic balance issues, and some have pretty serious issues. The biggest problem with economics is using built-in resources in ways that cause competition with the vanilla content or with other mods. For example, Botania and Thaumcraft have a fair amount of content that uses Ender pearls, gold, and diamonds. Most major mods have some economic flaw like this.
Botania really fails hard with terrasteel, where one bar of terrasteel costs an iron bar, an Ender pearl, and a diamond. The iron is not a terrible problem, especially given that the equipment made from terrasteel replaces your iron or diamond equipment. The Ender pearl is a very high cost though, given that Endermen are generally rare, and they are notoriously hard to farm. The diamonds are a less dramatic cost, because the terrasteel is taking the place of diamond or lower tier equipment, but now we are competing with vanilla on two equipment materials that are fairly limited. This makes getting terrasteel very frustrating, because first you are spending a lot of time mining when you really want to be doing other things, and second, the mining itself is consuming some of the materials you are trying to collect. It's true, the terrasteel tools have some pretty awesome time saving features, but by the time you finally have all of the materials to make them, you have already spent so much time getting the materials that the time saved does not feel like it will ever make up for it. It also does not help that after spending so many hours mining, you just don't feel like mining ever again, making the nice tools a lot less motivating to use. Ender pearls are also a problem when it comes to making the elf portal. This portal basically opens up the second half of the content in Botania. Unfortunately, you have to craft a set of equipment that is fairly heavy in Ender pearl cost to make the portal work. I spent tens of hours during one game trying to find Endermen to kill for Ender pearls. I had the portal completely constructed, and I only needed a couple more Ender pearls to power and open it. After days of spending a few hours a day hanging outside at night looking for Endermen to kill, I gave up. I got one spawn, and it did not even drop a pearl. It was beyond frustrating, and now when I even think about opening a portal, it feels like an insurmountable task. Botania also has a few items that cost a lot of gold. If you want to automate anything in Botania, you need hovering hourglasses as redstone timers. Unfortunately, each one costs four gold bars, which is quite a lot. Yes, you can make gold and iron farms, and once you get to the End, Ender pearls are really easy to come by, but all of these things take a lot of time and planning. I'll come back to this later, but part of the issue when it comes to stuff like this is that I have done it so many times already that it feels incredibly tedious when all I want to do is experience the content of the mod. Where Botania does really well is in the resource it adds. Botania adds mana to the game. Early on, it is hard to generate mana in large quantities, but by the time you need it in large quantities, it is easy to generate in large quantities. Mana production relies mostly on renewable resources. Some methods can generate manage by consuming non-renewable resources, but most have renewable options. For example, mana can be generated using food or charcoal as fuel. Automating food production is easy even in vanilla Minecraft, such that there does not need to be any competition between vanilla and the mod. Botania makes automating food production even easier, with the hovering hourglass taking over the role of a larger and more elaborate redstone clock (though at a high cost in gold). Automating charcoal production is much more difficult before the elf portal is opened, but charcoal is generally not terribly difficult to manually produce in significant quantities. In general, Botania's economic balance when it comes to its own resources is quite good, but it does a poor job of economic balance when it comes to its use of vanilla resources.
Thaumcraft has similar issues to Botania, though perhaps not as severe. Part of the issue with Thaumcraft is timing related though. Early Thaumcraft has really poor balance when it comes to iron and gold. Thaumcraft especially competes very strongly with vanilla uses of iron. The last time I played Thaumcraft (a month or two ago). I found myself spending around 20+ minutes underground mining for iron for every minute I spent above ground doing anything with Thaumcraft. I burned through iron so fast, and I frequently found my Thaumcraft progress stalled by lack of iron. For a significant period of the early game I did not even have iron armor, because all of my iron was going to Thaumcraft stuff. Eventually I did start accumulating significant amounts of iron, but right around that time, I started hitting the same problem with gold. It was less severe, but I was still spending more than half my time mining for gold for a while. Thaumcraft does have an ore doubling mechanic, but early in the game it is too expensive (and environmentally harmful) to use a lot. The most frustrating thing, however, was (again) Ender pearls. There is one type of resource in the mod that has no other source except Ender pearls, and Ender pearls only provide a very small amount of that resource. Thaumcraft is not as bad on this as Botania, using this resource only in limited amounts for some pretty late game stuff. Unfortunately, that late game stuff is pretty trivial to unlock somewhere around mid-game. Worse, the mod does nothing to clarify the fact that this is late game stuff, so when you unlock it, it feels like you should be able to (and maybe need to) use it right away, when in reality, the only way to use it effectively is to farm Endermen in the End. For a majority of its resources, Thaumcraft is actually very well balanced. Nearly all of its resources are produced from vanilla content. Half of those that are not displace vanilla resources, but they displace resources that are plentiful and farmable (trees, mostly). Thaumcraft does add some resources, but a vast majority of its resources are derived from vanilla resources. For a most of those resources, it does an exceptional job of balancing. In part, this is because nearly everything in vanilla can be turned into Thaumcraft resources. Thaumcraft does not rely as heavily on scarcity for resource control as it does side effects. You can easily obtain enormous amounts of most of the resource types quickly and easily, but the consequence is that your land becomes diseased and extremely inhospitable. The motivation to only produce what you really need is pretty strong. The places where Thaumcraft fails is where it relies on the scarcity of certain vanilla materials to control the availability of some very valuable resources, because in those places it ends up competing with vanilla features for resources.
Immersive Engineering also does a lot of things right but a few things wrong. It adds some resources to the game, and where it does this, it does extremely well. It adds uranium for power generation, and its rarity is perfectly balanced with its value. It has been a while since I played this mod, so forgive me if I get the occasional detail wrong, but I do recall some struggles. I seem to recall this mod having a serious problem with iron. Most of the machinery uses a ton of iron. The Crusher does double the ore obtained from ore blocks, but this only mitigates the issue, and the Crusher is not available till mid game anyhow (not to mention has an absolutely _massive_ iron cost, which won't be doubled, because you don't have the Crusher yet). Ore doubling is actually a common method for reducing resource competition between vanilla and mods, but there is only so much it can do, especially when it is a mid game tech. Immersive engineering also adds a power resource, Redstone Flux (RF), which is reasonably well balanced but not, perhaps ideal. There are three different kinds of wire, which can carry different amounts of current and different voltages. They are made from different materials as well, and this adds some challenges of its own. Some of the larger equipment in the mod has extremely high power consumption, and the result is that it costs a lot of resources (including a lot of vanilla) to power them. This is not actually as bad as it sounds though, because most of this is really late game stuff that is not easily accessible earlier. It largely just ends up being very time consuming. It does compete somewhat heavily with some vanilla resources, but the pacing of the mod makes it so that you are pretty likely to already have most of what you need by the time you have the mod progressed up to that point. The Immersive Engineering Excavator is especially useful in keeping up on resources, but it is pretty late game, which means a lot of its benefit comes too late to help a lot. It also costs enough iron to be a serious project to build even late game, when you think you already have a ton of iron. The last time I played this mod, most of the struggle was early on, and I spent a lot less time trying to keep up with vanilla and Immersive Engineering than with other mods. Part of this is that Immersive Engineering heavily supplements vanilla resources with its own, limiting competition. It also adds more automation stuff earlier on than other mods, reducing the burden in the early and mid-game. I found this mod less frustrating than some others, though it is still not perfect.
BuildCraft has some resource competition issues in the early game as well. It does not compete as heavily as some other mods, because it largely limits competition to resources that are less rare, but there are some points where excessive time has to be spent gathering resources. BuildCraft does manage to keep these pretty minimal though. It does this by tiering a lot of its content based on vanilla resources. For example, pipes can be made from a lot of materials, where higher tier materials give them better properties. This makes a lot of BuildCraft content available quite early on. There is a period between high iron competition and highly automated mining where things tend to drag on a bit, but it is actually pretty fast to get through this compared to other mods. The biggest difficulty with BuildCraft is probably the time spent on the liquid fuels required to automate at high speeds. These are made from BuildCraft oil, which either must be carried (in buckets or similar container) or piped to where it is to be refined. The refinery equipment is expensive enough that it is often more economical to just move it from one oil spring to another, but this is pretty tedious. Piping is another solution, but for any real distance, it gets expensive very fast (and then you run into chunk loading issues...). Unfortunately, this is not a completely automatable task either, because oil springs eventually run out. Once you have a good system, it is worth the effort, but early on it is very tedious. Overall, BuildCraft does a fairly decent job with game economy. It has a few points where things are difficult for a bit, but it does pay that back fairly quickly once you get automated mining going. Once you reach this point, BuildCraft can even produce enough mineable resources to support a couple additional mods. BuildCraft's massively advanced automation control stuff also really helps reduce drudgery in the late game, but progressing to it involves a lot of drudgery. I have only gotten a little way into the circuitry and such, mostly because the more valuable chipsets are so expensive (using iron, gold, diamonds, and Ender pearls). But, these are not critical to solid automation in the mod. The more expensive stuff is more about convenience than anything, so doing without them is not a huge burden. Overall, BuildCraft's economy is pretty solid. There are a few hiccups, and there are some failures in the very late game stuff, but none of this is anything terribly critical. My biggest frustrations with BuildCraft come from inventory management when there are such huge quantities of resources coming in, but this is better than not enough, and there are good support mods specifically for dealing with this problem.
Mystcraft only produces one serious challenge when it comes to economics. This is leather, and it brings up another issue some of the above mods occasionally have. The problem is that sometimes, there will not be any cows near spawn. When I say "near", I mean, on two occasions in the recent past (out of the 5 or 6 worlds I have created recently, which means about 1/3 of the time), I have landed half a day's (MC time) boat ride from the nearest cows or more. In at least one, I never did find cows. Luckily, that time I was using a mod that made it pretty easy to make leather from rotten flesh, without first needing leather to start the mod off. (The other time, I was playing Thaumcraft, and I am not even sure how far I ended up going from spawn to find a cow just so I could craft the mod documentation/progress book. I think I ended up holing up for at least one night during the journey.) Mystcraft requires a lot of leather if you are doing it right, and when you cannot find any cows, the mod is straight up impossible to do anything with. Now, I cannot blame the mod entirely for this, however, mod makers should be aware of cases where a critical material for the mod may be rare enough to seriously hold up the mod progression. For leather, a simple solution would be to just add a recipe for crafting rotten flesh to leather. It does not have to be one for one, and it can even be more expensive than just the rotten flesh, though if leather is a major resource for the mod (Mystcraft, for example), the cost should be quite low. Two good options I have seen are four rotten flesh crafted in a square to get one leather, and cooking a piece of rotten flesh in a furnace turns it into leather. One costs four for one, and the other costs fuel on top of the main ingredient. Neither is terribly overpowered either. The point is, mods should be aware how scarcity of resources used in the mod can vary. In the current game I am playing with Botania, I have not found a biome with emeralds yet. If I needed emeralds for some critical, early part of the mod, this could be a serious problem. (As it is, I have found a village, so for the mid to late game, I do have access to emeralds.) Overall, Mystcraft is a very well balanced mod, when it comes to economy, but it does occasionally have issues, because it fails to account for a scenario that is not terribly uncommon.
The last mod I want to discuss is Twilight Forest. I have far less experience with this mod than the rest. (In fact, I am currently playing it for the first time.) From what I have seen so far, it is very well economically balanced, mostly because it primarily focuses on non-resource content. The only resource (vanilla or otherwise) I have spent on it is a single diamond, to open the portal to the forest dimension. While diamonds are legitimately very rare, a one time cost of a single diamond for the mod only barely competes with vanilla. One diamond ever is not a significant burden. In the worst case, it could be a cost of 30 minutes to an hour of mining, in exchange for a ton of additional content. By focusing on content that has no resource economy, Twilight Forest has managed to almost entirely avoid the economic issues common in other mods.
It should be pretty easy to see, at this point, how some mods harm the economy of the game by adding resource competition without sufficiently improving access to those resources. When mods are combined though, resource issues can be further amplified. Thaumcraft and Botania both expect a certain level of access to Ender pearls, and neither provides a decent means of increasing production. This means that now the mods are competing with each other in addition to the game. Similarly, Thaumcraft and Immersive Engineering both do ore doubling, but when you play them together, now you need three times the ore but neither can do more than double ores. Mod authors should also consider how competition with other mods is going to affect their mod economies. When you have multiple mods and the vanilla game all competing for the same resource, players are not going to enjoy the game as much. Generally this will result in players picking one or two mods to focus on, and in big mod packs, odds are your mod won't be one of them. This can be mitigated by adding support for other mods to your own or by using standard resources that can be shared between mods without too much competition, for example, a significant number of mods use the Redstone Flux energy that Immersive Engineering uses, allowing players to use the same power generator for multiple mods, instead of having to construct a different generator for every mod. It is important for mod makers to at least consider how their mod will play with others, and that includes their impact on resource economy.
The last thing to keep in mind about resource economies in mods is that most people playing with mods have a fair amount of experience under their belts. To be clear, they have already experimented with automation, they have already played through the early game many times, and they are not playing your mod because they want to spend hours upon hours of more time mindlessly mining. They probably won't mind spending the same amount of time in early game that they would in vanilla, but they don't want to spend a ton of extra time in the early game, because your mod is competing for resources. If your mod is going to compete for resources in the early game, make sure there is a fairly immediate benefit that makes up for it. Things like more effective mining tools are more appropriate early on than later, once the player has already spent far too much time mining. Providing the player with quality of life improvements early on is far more valuable than later. Instead of making the enhanced tools purely late game items (like both Botania and Thaumcraft do), offer mildly enhanced tools early game and push back some of the more impressive content till a little later. A pickaxe that can mine a 3x3 area that is easily accessible between the iron and diamond tiers is not game breaking at an expense slightly higher than iron, and players will appreciate it far more than many things mods offer at that point that are often more valuable later on. Experienced players neither need nor want the long slow early game, and they certainly don't want it dragged out longer by your mods. So instead of purely trying to add end-game content, also add some early game content that will make it a little easier and faster for seasoned players to get to your awesome late-game content.
Balancing game economies is tough by itself, but it is really easy to break a well designed game economy by throwing in new content without fully considering how it is going to affect the existing economy. And this includes time as well as resources. If you are making or considering making a mod, please keep in mind that every unit of a resource your mod uses is a unit of resource that cannot be used for anything else. If your mod is going to compete with vanilla or another mod for resources, make sure your mod provides something to mitigate that, otherwise your players will be spending a lot more time doing things that are boring and grindy, instead of having fun with your mod. And likewise, keep in mind that mod players are generally experienced. They don't want to spent a ton of time in the early game because of your mod. Throw them a bone. It's not terribly difficult to speed up the early game a little bit without going too far. Again, keep in mind that the sooner the player is able to really use your mod content, the more they will enjoy your mod. The last thing you want is for players to spend so much time and energy on other mods that they do not have time to enjoy yours. Instead, make your's the mod that gives them the time to play all of them. Maintaining balance is tough when making games and when modding games, but if you make sure to pay attention where resources are coming from and how much time is required to obtain them, it is not terribly difficult to avoid seriously upsetting the balance. We have a lot of very good mods out there, but with a little tweaking on economic balance, they could be absolutely epic.
