Let's look at each of these in more depth. I'm going to take the first two together, since they combine in many ways.
One consequence of the first two is that "grief players" – those players who get their fun by messing things up for other players – are pretty much unknown in paper RPGs. First off, since the group is supposed to be cooperating, there are few opportunities for grief players. Second, since all the players often are friends outside of the game, a grief player runs a high risk of losing those friendships. Lastly, and most important, since physical presence is needed to play, it's very easy to exclude a grief player – just don't invite him/her back. If the grief player shows up anyways, ask them to leave. If they flat-out refuse to leave, you can throw them out bodily or call the police, depending on your inclination.
That's a fairly extreme example, but there are other, less extreme differences that arise. For example, many paper RPGs allow characters to grow vastly in power in a relatively short period of time. In a paper RPG, that works out well – it lets the characters keep running into fresh, new challenges. In a multiplayer online game, however, when characters can do this and are competing with each other (not necessarily directly fighting, but at least competing to kill monsters, complete quests, etc.), this causes such problems as experienced players who raid "newbie areas" for quick and easy experience points and loot.
The third difference – the human gamemaster – is also involved here. One of a GM's responsibilities is to make sure that the game is challenging to the player characters. Too easy is bad, but too hard is bad as well. In a paper RPG, the player characters are usually relatively close in power, so it's not too hard to find something that's challenging for all of them. In an online multiplayer game, however, people start playing at different times, and therefore you have characters in the game with widely varying power levels. Making the game challenging for all players, while not being too hard or too easy for anyone, becomes much harder.
Further, since the GM implements the game's rules (the fourth difference), a GM in a paper RPG can "fudge" the rules if he/she makes a mistake in estimating what will be challenging for the players. If an adventure is turning out to be too easy, the GM can add extra foes, remove a clue, make the NPCs be less cooperative, or make any number of other changes while the game is going on. And, of course, if the game is too hard, the GM can do the reverse.
Online games generally can't afford to have someone to watch each adventuring group of players to make sure they're not wandering into something that will quickly kill them, or to make sure that they're not going off and tearing up stuff that's meant as challenges for lower-power characters. Even if they could, trying to change the game in real-time is a much more difficult task than it is for a paper RPG GM – difficult enough to be effectively impossible in most multiplayer online games.
The upshot of all this is that, before bringing in a concept or mechanism from a paper RPG, you need to take time to think about these differences and how they may affect what you're trying to do.
For example, you'll sometimes see people arguing that long training times should be needed to improve characters, or that characters should need a long time to heal after being wounded. These changes would make the game more realistic, more of a challenge, and help keep people who can play the game ten or twelve hours a day from dominating the game to the exclusion of gamers with... well, real lives. There are paper RPGs that do these things, and they work fine there.
That's all true... but it ignores the fact that the reason these things work well in paper RPGs is that it's easy for the GM to "skip past the boring parts". The characters might spend three months healing and training in new skills... but the GM and players simply take a half hour or so to figure out the results of all that, then move on to the next interesting part of the game.
In an online multiplayer game, you don't have that luxury. Someone whose character isn't injured or training isn't going to like being told, "well, your character doesn't do anything significant for the next three months of game time" so time can be skipped ahead for someone else he/she probably doesn't even know. Players who are competing against each other certainly won't like that, and in player-versus-player setups, the "up" player might well want to make sure that the "down" player doesn't ever get to finish healing!
Well, this is actually stretching on a lot further than I thought it would, so I don't think I'm going to cover text adventures this time. Let me know in the forums if you think this sort of coverage of differences is useful... if it is useful to people (or if no one seems to be responding), I'll tackle text adventures next time. Otherwise, we'll press on to a new topic!
