Since the last essay was mostly abstract, in this one, I wanted to give a few examples of games that have implemented randomness in a way that significantly impacted the game, for well or ill.
"Gotta Catch 'em... Nevermind" - Ni No Kuni
I heartily recommend this game to my friends, albeit with one severe caveat: don't try to recruit all of the monsters. There are approximately two to three hundred to catch, depending on the amount of leveling the player wants to do. The recruitment rates are constant (with a one time ability that boosts all rates a fixed percentage), so we are firmly in the constant drop percentage scenario I wrote about in the previous essay.
The problems I mentioned about constant drops are compounded in this case because there are so many different monsters that, even if the drop rates look high, the player is literally more likely to win the Powerball jackpot than to not get severely unlucky attempting to recruit at least a couple of creatures. This issue is again compounded by the fact that the player will be getting several taming events from some of the other creatures while there will generally be one creature in the region that will elude capture. The game is giving mixed signals; taming is presented as easy to get because taming events happen very often while there are several specific creatures that will elude you. This sours the moment-to-moment play experience because the player will be focused on how unlucky they feel, due to the fact that the designers have basically ensured that approximately every couple of regions, some creature will take much longer to catch, even though the tame rates probably all match.
In one single decision about randomness, the designers here go a long way toward spoiling all the excitement and wonder everything else in this carefully crafted, beautiful game is working to build.
In case you were wondering why I chose to talk about Ni No Kuni instead of Pokemon, the latter softens this problem somewhat by having items like Master Balls, which are items that allow guaranteed capture of any creature they are used on. In the long run, the deeper the player gets into Pokemon, the more they will experience something similar to Ni No Kuni, especially if the player wants to tame Pokemon with specific natures or only train their Pokemon against specific creatures.
Low Constant Drops Done Well - Castlevania: Symphony of the Night
In Castlevania: Symphony of the Night, almost every enemy has a couple of items that they can potentially drop when defeated. Noteworthy here are about twenty possible high level weapons and other powerful items that are only obtainable from enemy drop. The weapons available through the store or found in the course of the game are powerful enough that there's no need to have the drop-only weapons, and there is no achievement for doing so either, as this was a PlayStation 1 game. The dropped weapons are generally more unusual than excessively powerful and tend to force the player to play in a different way and look at the environment differently. The key difference here is that as all meaningful drops are quite rare late in the game, the player is taught by the randomizer not to expect anything, unlike Ni No Kuni, where the player is getting constant reinforcement that taming should be easy. Therefore, any rare drop gotten is more likely to be seen as a fortuitous gift, rather than an eventuality.
The rates are such that there is a good chance that the player is likely to get an unusual weapon at some point in the game if they tend to explore, something the game wants you to do anyway. The weapon is powerful enough to entice the player to spend some time learning to use it, and the player can never get a weapon that is totally incompatible with the character's skills. Through using this weapon, the way the player must approach the game changes dramatically. Therefore, the randomness adds a tremendous amount of replay value without requiring new maps. For a genre that has traditionally relied on hand crafted maps, this is a fantastic solution to replayability.
A Kinder Looting System for Quests - World of Warcraft
The pacing of World of Warcraft is decided by progressions of quests, and many of these quests take the form of killing some number of the same creature to gather some number of quest items they alone drop. Before the Wrath of the Lich King expansion, the drop rates for these quest items tended to be high, but like Ni No Kuni, when the designer demands the player succeed at repeated random actions, the player will go on lucky and unlucky streaks. Blizzard found out that players remember their unlucky streaks more vividly; unlucky streaks, after all, bloat and pad the time required of what is a task that was not designed to be interesting for that long. Blizzard's solution was to implement escalating drops for quest items in order to balance the pacing of these quests. This also has the effect of capping the maximum unlucky streak the player could suffer, leading to a more even game. The interesting side effect that the change had was to additionally decrease lucky streaks, as well, and Blizzard revisited and increased the initial drop rates to allow players to have more consecutive drops, allowing players to feel luckier.
Note that this system only applies for quest items, which are not the powerful weapons, armor, and items that WoW players seek in the long term so this change doesn't really effect the economics of the World of Warcraft, just the pacing. It does seem rather cruel to have the randomizer teach that unlucky streaks will be capped for common quest items, but the player may have attempt for years to get the ones they really want. Part of Blizzard's motivation on not escalating the legendary drops stems in part from wanting repeatable end-game content while maintaining rarity of legendary items on servers so the comparison to single player games gets a little harder from all of the other interpersonal and economic forces involved. I'll write more about a similar situation in a game that's more single player focused in the next section.
A Couple of Shots and You're Out - Demon's Souls
Demon's Souls allows for an interesting experiment. The game features two kinds of randomness that we've talked about: two of the items that yield the best weapons are only found from an enemy with limited respawns. It is a ten percent probability drop, which can be raised to about twenty-five percent if you understand the mechanics, and there are at most six chances you have per game to get it. The game has a New Game+ feature, which allows the same character to play through the game again while retaining items, so the drop will be available next game cycle if you didn't get it in your first. This dramatically limits your time to attempt to farm the item, and the monsters that carry the item are weak, but quick. Once the player understands the stakes, which generally takes overlooking some of these creatures or letting them get away, they tend to focus energy. The stakes are raised, and it's an experience, for well or for ill, that stays with the player. These drops have generated resentment, but in general, the pain is over quickly, and the players accept it as part of the experience. It also helps that the unique multiplayer aspect of the game has allowed people to learn to trade items with each other.
What has generated more resentment than anything else in the game is another, less powerful item, which is an extremely rare -- 1/200 under optimal conditions -- drop from an infinitely respawning monster. To give a point of reference, there is nothing else in the game that drops so small of a percentage of the time on any monster. The time to kill one of the monsters is about ninety seconds once you hone your path, so on average, the player is looking at doing exclusively that for about five hours on a game that takes about twenty hours to finish a cycle. What's worse is that there's a twenty percent chance you won't get one after doing a ninety-second loop for seven and a half hours. If you search the message boards, this item has about three times the number of rage threads that the previous items do. The experience is so uneven that for each player who gave up farming after ten hours, there's one who got it in five minutes. The variance in gameplay is huge, especially when you can see that the ten hours became rote mechanical behavior. To add insult to injury, this process, if it goes very long, will cause the player to accumulate a tremendous number of levels, almost trivializing the rest of a game whose signature calling card is its difficulty. As the downside experience is so great, any bonding done over this item tends to be resentment, instead of excitement. This dark cycle is all reinforced by achievements that require obtaining the item.
The World's Just Made That Way - The Binding of Isaac
This game gives an extreme example of limited availability drops. All game sessions are randomly generated and last, at most, about an hour; this sets the stage for the world to only contain a small number out of a large pool of potential items. As the items vary greatly in power, the player will have wild variability between play experiences, with a bias toward feeling underpowered. The great care taken here is that the theme of the game melds very well with the experience the randomizer gives; life is not fair, the player doesn't know what will happen in life, and the player must find a way to work with the hand dealt to survive.
The saving grace to having a terrible allotment of items is that each game is short; there isn't much sunk cost in any one run. Finding yourself in a nigh-unwinnable situation thirty minutes in creates pressure to perform, and if you fail, well, you got unlucky. If you succeed, the victory is generally a fantastic one; you really did overcome the odds. If thirty hours into a game, you didn't have a viable path to winning because the good items weren't available in this game world, the experience would undoubtedly be a bitter one instead.
To Sum Up
The key point I'd like to make with these examples is that understanding the longer term consequences of the randomness used in your game is extremely beneficial to adjusting the moment-to-moment play experience. There is no kind of randomness that is universally wrong to use for drops, but the context of the design vision is king here and should be used to guide your selection. When there is a disconnect between what you are teaching the player and what the randomizer teaches the player, there will be unnecessary dissonance between the game the player was attracted to and the game the player is playing. Ni No Kuni's moment-to-moment play experience felt like a chore, which goes against the magical feeling presented by the story and art. Symphony of the Night's randomizer reinforced the idea that the Dracula's Castle was ever-shifting because you generally didn't see the same rare drops twice in two game cycles. Just as people rightfully deride ludonarriative dissonance, a randomizer can also subtly undermine what the story and background of a game are attempting to create.
As I wrote in the first article, people are not taught to understand randomness particularly well so experimentation and simulation of the designed randomness will go a long way in ensuring that your design vision is realized as a cohesive whole.