
I often wonder what it is about World of Warcraft that has kept me so entranced for such a long period of time. Over the past two and a half years of playing, I have only taken one substantial break from the game. But even during this break, I still kept my account active and would frequently check on my character to make sure that my pet was still at maximum happiness and Onyxia hadn't conquered Stormwind.
So what has given World of Warcraft such lastability*? My theory is that the game has a great deal of instant gratification. Most people can get a WoW fix in just a couple of hours and usually have some small reward to show for their minimal efforts. Factor in an extremely lax death penalty and you have a slap-happy lollercoaster ride that dishes out free levels like bank lollipops.
To give you an idea of just how much easier WoW is in comparison to other online games, I took a half hour to compare it to the four MMORPGs that preceded my WoW account.
Disclaimer: Many of these games I played for only a few months from the original release date, so my information will not reflect patches, expansions, or added content. For this reason the following is completely unfair and written in past tense.
Everquest
For players of the original Everquest, the game felt more like an unpaid 60 hour a week career than a relaxing off-time pursuit. During the first few levels of the game, players would find themselves running around Norrath in order to kill various low level mobs with the dream of one day killing slightly higher level mobs.
The formula for the game was to find a monster, kill it, and wait 15 minutes for your health to regenerate. Get up, go kill another monster, then sit down and regain health again. Repeat this process 20 times over the following 6 hours and convince yourself that you’re having fun. Then get trained by a Paladin and lose a level.

Caster classes had it worse as they were forced to “meditate” in order to gain back their mana. Meditating involved staring at a spellbook graphic that filled the entire screen. This process is as painful as it sounds, and was made even worse by the fact that the spellbook graphic was crappy.
This wait became even greater as you leveled, forcing players to spend twenty to thirty minutes between fights (keep this in mind the next time that you can’t wait for your priest to get back from his bio to pull Ragnaros).
The downtime between fights was so long that players started threads on the Everquest Forums on the subject of what people would do while regenerating their health and mana. The responses ranged from watching television, to mapping the human genome.
Another exhausting aspect was the experience system. We’re all familiar with experience scaling for levels - the higher a player’s level, the more difficult the experience gain. Well EQ had screwed up the math and the end result was hell levels. Hell levels started at level 30 and were levels where players had to accumulate an enormous amount of experience to advance their character to the next level. If players were able to make it to the fabled level of 31, they would have four levels of experience bliss before reaching the next hell level at 35.
In a year, a devoted player’s main character was usually level 30.
Grind Level: Caster Class + Hell Level + Paladin Train = -1 year's work
Dark Age of Camelot
Dark Age of Camelot was a fairly decent game, but only because it was more visually attractive than Everquest and had a cool realm vs. realm combat system. For people who didn't have the time to reach level 50 to participate in RvR, the game was craptastic.
A session of DAoC generally consisted of grinding mobs by yourself or with a group. This was before dungeon instancing, so "special content" was a hole in the ground with a greater concentration of mobs and a bigger version of the mobs at the end. I would use the word "boss" to describe these larger mobs, but they were more like assistant managers, or shift supervisors. Leveling took patience, stamina, and an easy to reach phone with local food delivery numbers programmed into it.
Dark Age of Camelot didn't really offer quests. I say this passively because one time I talked to a dwarf sitting next to a tower. He said something to me like “would yeh help meh defend meh keep, lad?” I must’ve clicked “yes”, because the next thing I knew a slew of elite creatures came running down the hill killing myself, the dwarf, and about six other people in the area.
General chat exploded with "WHO TALKED TO THE DWARF!?!?”
The grind was also made difficult through a poorly designed travel system. The world of DAoC was enormous even by today's MMORPG standards and at launch there were only about five horse routes to take you through each region. Most horse routes wouldn't take you exactly where you wanted to go, so you would have to jump off your horse at the right point in the route. However, often you would start typing text without having your chat cursor up, inciting a wild flurry of game menus and then dismounting you in the middle of BFE. If this happened to you, your best bet was to just reroll a new character.

Also, DAoC didn't have an in-game map navigation system, so in order to figure out where you were going you would have to consult a 10'x10' paper map that came with the game. To complicate this further, the map didn't contain the names of any of the smaller villages or regions. This omission forced us to navigate via tiny landmarks on our maps, or enlist the help of experienced mountain Sherpas.
Not that you even knew where to go most of the time. Your best hope was to kill creatures in a certain region until you were too high to get experience from them and then hope that there was an adjacent region with the next level of mobs. Somehow I was able to reach level 26, but lost the will to go further after that point.
Grind Level: DWARF QWEST FTW!!!
Planetside

Planetside was enjoyable enough. Character creation involved visual customization and the allocation of ability points to increase proficiencies in various skills. Players could choose proficiencies in piloting, heavy weapons, engineering, subterfuge, armor wearing, and pharmaceuticals.
The problem with the RPG side Planetside was that there were very few incentives to level a character. First level characters started with enough proficiency points to pretty much become experts in any chosen field, and with no items or currency in the game, Planetside left little reason to invest much time in any one character. Whenever I got tired of being a fighter pilot, I would just start a new character that could drive a bus, or program Java.
In addition to normal experience, there was also a Command Rank system that rewarded players for leading squads into battle. However, Command Ranks were often undesirable because players would not receive regular xp while functioning as a squad's commander. Obtaining Command Ranks was also a very slow process which would only grant cool abilities at the highest ranks. Lowers ranks only allowed characters to do little annoying things such as set waypoints for their squad and doodle on their squad member’s game maps (seriously). Coupled with these abilities were trivial visual upgrades which included a huge golden boot upgrade and a fanny pack upgrade (seriously).
Grind Level: Uh, I'm cool
City of Heroes
City of Heroes took the classic questing formula and tweaked it a little bit. In CoH, Superheroes earned experience through running errands from various "contacts" in the city. Contacts served as NPC quest givers that gave you more and more work at increased difficulty as you completed their quests.

Quests in the game ranged from beating up a gang of bad guys in the park, to beating up bad guys in an abandoned office building. But I don't fault CoH for this formula, cuz when I put on a superhero costume, I expect to beat up some bad guys (or at the very least walk around a convention center getting autographs).
The only downside to CoH was the leveling curve, which was fairly steep. After getting to level 15 or so, the pace of the game began to slow down dramatically. However, a brilliant "sidekick" system compensated this through allowing low level players to be mentored by a higher level player. This option made the low level player's effective level almost as high as the higher player's level so the low level player can quest with the high level player in high level player places without having the penalty of being a low level player.
Q: So, if I have a character that is level 45, a character that is level 32, and a character that is level 16, which character will be the sidekick?
A: The one with the lamest costume.
Grind Level: Excelsior!
World of Warcraft
Quests for everything - including mob grinding, delivery quests which test a player's ability to use a roadmap, no experience penalty from death, double experience gain earned through not playing, and some of the most advanced bot programs ever conceived by AI programmers.
And we wonder why the 70 Warrior in our group doesn't realize he has a defensive stance.
Grind Level: Ice with a flamethrower
*While lastability is not a "real word", it should be.