Figured it might be good to re-post this where others might be able to find it since it was such a length write-up:
There are so many nuances to ARPG design that I could probably write a book about it and there are many factors that I think contribute to the success of Diablo 2.
On the subject of replayability though, there is one sort of high-level factor that I think is a key predictor in determining how much time a given person will likely spend playing and replaying a game. I call it the “profit & loss” ratio and Diablo II has one of the best P&L ratios I’ve ever experienced.
Basically, the idea goes something like this…
Profit is all the things that are pleasing or enjoyable about playing a game. There are two main categories of profit: fun and reward.
Fun is the immediate, second-to-second feeling of excitement and enjoyment that you have while you’re playing. You feel fun right when it is happening but fun is a fleeting feeling that doesn’t really stick around once you stop doing whatever was fun. I’ve seen many instances where people seem to have a ton of fun doing something or playing a game and then after they just never think to go back and play again. You’d think since fun feels so great when its happening that we’d want to keep repeating it but it seems the brain is more interested in reminding us about rewards. Fun is important to keep us playing long enough so that we can experience reward. If people are having fun, they’ll sit down for a longer session of gaming but it is the feeling of reward that lingers with us, that our brain wants more of, that keeps us coming back to play again.
A few types of things that generate profit:
Stimulating combat
Exploration / seeing cool things for the first time
Advancing our character
Collecting items and gold
Thinking about creating new / better character builds
Socializing with friends in-game / meeting new people
Beating difficult enemies / difficulty modes
Etc, etc, etc…
Working contrary to all this is loss. Loss is basically tedium, unrewarded effort, frustration and so on. The funny thing about loss in gaming is that it can often come from the smallest things. That extra click to open a UI panel, load times, tedious actions that we must repeat. The worst type of loss is that which is incurred before you encounter profit - everything you need to do before you can start playing. Anyone ever been bored and considered firing up an old game but then thought about the nuisance of reinstalling it or just how long it takes to load up and decided to go do something else?
Over time, eventually profits start to diminish and loss tends to get worse. That really cool thing you saw the first time through is always a little less cool each time you see it. That long load time to get in-game and all those extra, pointless clicks on the UI get more tedious each time. Even some things that may have added to the enjoyment initially can become tedious quickly. Maybe the ultimate every-day example of how adverse we are to effort is leaving the refrigerator open while you pour a drink because closing and re-opening it seems like too much of a nuisance even though cold air is pouring out the entire time.
For me, one thing that can become extremely tedious is going back through quests that have lots of small steps. It might be great the first time, hearing each NPC’s back-story and perspective, following along and going through the steps to unlock the next part of the story, but once you’ve done it, if there is no alternative way to play, you already know what is going to happen. Having to run back and forth to hear different NPCs repeat the same lines you’ve already heard just so you can be assigned a quest that you already know about before you can unlock the gate to move forward becomes quite monotonous.
D2 has a great P&L ratio because it launches quickly, you can be in-game within seconds and once you enter the world, you can just teleport right out into the action without a lot of preparation. You can go from clicking on the executable to killing in like 10 seconds. It is one of the few RPGs where you feel like you can accomplish something meaningful by playing 15mins or less. The combat is fast paced, fun and you can even play semi-effectively while slouched in your chair drunk with only one hand on the mouse should you choose to. The game is a constant stream of slot-machine style reward. There is always another item to get and always another loot chest or enemy at the edge of the screen that might drop something good. You get to make tangible and lasting decisions about the advancement of your character through the allocation of skill and attribute points. You get numerical proof of your increasing power and there is always something you can work at making just a little bit better. Even as you’re playing one character, this continual thinking about new builds and gear you discover that would be great for a class other than what you’re playing basically lays the foundation for your next replay.
Where D2 is really great is in the way it reduces many of the most common sources of tedium. You generally don’t have to talk to NPCs, you can finish Act1 without ever talking to anyone. You can stumble upon and complete quests while out adventuring in the world without having to first talk to NPCs to receive them. Even the towns are small and efficiently designed so there is minimal running around. When you’re on your 4937459327523957 play-through of D2, even just the small distance from the portal to the merchant or up to resurrect your mercenary can feel long but think how much shorter it is than most games. A lot of studios seem to want to create these giant towns, which are often initially impressive but can become a source of tedium over time if the few places you routinely need to visit are spaced out by a bunch of useless filler (of course, this isn’t necessarily the case in games where gameplay takes place within the towns). Finally, my nemesis, scripted scenes that you’re forced to sit through… All these things, when done well, can make for a great initial experience but they tend to reduce replayability over time. Depends what you want in the end, the best initial experience with limited replay value or maximum replayability to keep you coming back time and again.
Anyway, you get the idea. To me, the greatest success of D2 is the profit to loss ratio. There always seems to be more reason to go back and play than not to.
EDIT - Added this post in that was a response to a question below:
The challenge and the frustration that might occur in dying to a boss is not really what I meant by “loss”. At least, so long as you understood why you died and knew what you could do to improve.
In this context, frustration can be part of a larger cycle of reward that actually enhances the feeling of reward when it happens. In fact, I remember reading an article that discussed how the supposed purpose of anger was to heighten our focus and motivation to overcome obstacles. So, I think unless you become hopelessly frustrated to the point that you just flip a table over and walk away, this type of frustration can actually motivate us to play more / play more intensely. A defeat can also serve reinforce the importance of collecting equipment and refining your character.
The type of loss I’m talking about has no long-term positive effect. For example, in one game I played a while back, it had gold auto-pickup but it was really touchy and you had to get right over the gold and sometimes pause for a second before it would pick up. It was incredibly annoying because picking up gold isn’t something you expect to be challenging and the auto-pickup “convenience feature” actually made it worse than having to click on it due to it’s inconsistency. When performing mundane tasks in games is more difficult than doing them in real life, there is a problem.
You expect boss fights to be difficult though and if they’re done right, when you die, even though you may feel frustration and direct it at the game, inside you’re really frustrated with yourself and want to do better.
The Andariel fight in D2 is one of my favorite. It always felt very challenging and intense when you got their early, with a lower-level character because she could kill you pretty quickly if you weren’t careful.
