Along with character classes and levels comes the natural tendency to classify campaigns according to the level of the characters. Experienced players speak of "low-level" or "high-level" games in different terms and, indeed, such games are different from one another. Also differing from game to game, however, is the definition of high level.
Defining "High Level"
What constitutes a low- or high-level game is a matter of taste. Generally, DMs and players find a range of character levels that is comfortable for their style of play. Campaigns that commonly have 4th- to 8th-level characters consider those with 12th-level or more to be high level, while those with 12th-level characters set the limit closer to 18th or 20th level. While there is no set break-point for high level, character duties and responsibilities begin to change around between 9th and 12th level.
Generally, players find battling monsters and discovering treasure to be less and less satisfying as time goes on. Their characters' abilities are such that monsters need to be almost ridiculously powerful to threaten them. Treasures must be vast to make an impression. While incredible foes and huge treasures are good once in a while, the thrill quickly wears thin.
Changing Campaign Styles
When players begin to get jaded, consider changing the style of the campaign. Higher level characters have great power—they should have adventures where that power influences and involves them in the campaign world. As leaders, rulers, and wise men, their actions affect more than just themselves, spreading outward in ripples over those they rule and those they seek to conquer. Political machinations, spying, backroom deals, treachery, and fraud become more pronounced. While these elements can play a part in a low-level campaign, at higher levels, the stakes are much greater.
Added intrigue can be introduced into a campaign gradually. For example, Varrack, a mid-level fighter, is appointed sheriff of a local village as a reward for his sterling deeds. He can still adventure as he has been accustomed to, but now he must also watch over the villagers. The DM has the local bandits raid the trade road. As sheriff, Varrack must stop them. He goes with a small group, only to discover a camp of 500 outlaws. Realizing he's badly outnumbered, he beats a hasty retreat, raises a small militia, and clears the countryside of the enemy.
With this he rises in level. In addition, his lord is pleased and grants Varrack stewardship of several villages, with sheriffs under his command. The neighboring baron (who organized and sent the bandits) notes Varrack's success with mild displeasure, planting the seed of a festering hate. More immediately, the craven and vengeful sheriff of the next village on the road (whose incompetence allowed the bandits to flourish) suddenly finds himself out of favor. He blames Varrack and searches for a way to bring the new steward down.
As the campaign progresses, the DM can slowly spin a web of intrigue around Varrack as enemies, open and hidden, seek to block his progress or use him to topple his own lord. Against the odds, Varrack may find himself destined to become the king's champion, gaining new titles, responsibilities, friends, and enemies along the way.
Above 20th Level
Theoretically, there is no upper limit to character class levels (although there are racial limitations). The material presented here takes characters only to 20th level—experience has shown that player characters are most enjoyable when played within the 1-20 range. Above 20th level, characters gain few additional powers and face even fewer truly daunting adventures.
Consummate skill and creativity are required to construct adventures for extremely powerful characters (at least adventures that consist of more than just throwing bigger and bigger monsters at the nearly unbeatable party). Very high level player characters have so few limitations that every threat must be directed against the same weaknesses. And there are only so many times a DM can kidnap friends and family, steal spell books, or exile powerful lords before it becomes old hat.
When characters reach the level where adventures are no longer a challenge, players should be encouraged to retire them. Retired characters enter a "semi-NPC" state. The character sheets and all information are entrusted to the DM's care.
A retired character still lives in the campaign world, usually settled in one spot, and normally has duties that prevent him from adventuring. While in the DM's care, he does not gain experience, use his magic items, or spend his treasure. It is assumed that he has income to meet his normal expenses.
The retired character can be used to provide players with information, advice, and some material assistance (if this is not abused). However, his or her overall actions are controlled by the DM, not the player who originally created the character.
If at all possible, player characters should be encouraged to retire as a group. This way all players can create and play new characters of approximately the same level. If only one player retires his character to start a new 1st-level character while all the others continue with 20th-level characters, the poor newcomer can't really adventure with them. (If he does, the player won't get to do much or the character will have a very short life expectancy!)
Some players may be reluctant to retire a favorite character. Explain to these players that retirement doesn't mean the character can never be used again. Be sure to create special adventures that require those high-level heroes to come out and do battle.
Every once in a while the old adventuring group may have to reassemble to deal with some threat to the kingdom or the world. It's the chance to show those upstart new characters just what a really powerful group can do! It also gives the players the opportunity to role-play some the their old favorites.
If the players see the opportunity to use their powerful characters, even infrequently, they will be less reluctant to spend most of their playing time with new, lower-level characters.